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                                                                     EXHIBIT 5.1

                     [LETTERHEAD OF CAHILL GORDON & REINDEL]
                                [80 Pine Street]
                              [New York, NY 10005]
                              [John Schuster, Esq.]








                                  June 27, 2001







Burlington Resources Inc.
5051 Westheimer, Suite 1400
Houston, TX  77056-2124

Burlington Resources Capital I
c/o Burlington Resources Inc.
5051 Westheimer, Suite 1400
Houston, TX  77056-2124

Burlington Resources Capital II
c/o Burlington Resources Inc.
5051 Westheimer, Suite 1400
Houston, TX  77056-2124

Burlington Resources Finance Company
c/o Burlington Resources Inc.
5051 Westheimer, Suite 1400
Houston, TX  77056-2124

         Re:  Registration Statement on Form S-3 (Registration No. 333-61600)

Ladies and Gentlemen:

                  We have acted as special U.S. counsel to Burlington Resources
Inc., a Delaware corporation (the "Company") and to Burlington Resources Capital
I and Burlington Resources Capital II, each a
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statutory business trust formed under Delaware law (each, a "Trust") and
Burlington Resources Finance Company, an unlimited liability company organized
under the laws of Nova Scotia, Canada ("Finance Company", and together with the
Company and the Trusts, the "Registrants") in connection with the Registration
Statement on Form S-3, Registration No. 333-61600, as amended through the date
hereof (the "Registration Statement"), filed by the Registrants with the
Securities and Exchange Commission. The Registration Statement relates to the
issuance and sale from time to time, pursuant to Rule 415 of the rules and
regulations promulgated under the Securities Act of 1933, as amended (the
"Act"), of the following securities with an aggregate initial offering price of
up to $1,500,000,000, as shall be designated by the Registrants: (i) senior debt
securities of the Company, in one or more series (the "Senior Debt Securities"),
which are to be issued under a senior indenture proposed to be executed between
the Company and Citibank, N.A., as Trustee (the "Senior Indenture"), the form of
which is filed as an exhibit to the Registration Statement, (ii) subordinated
debt securities of the Company, in one or more series (the "Subordinated Debt
Securities"), which are to be issued under a subordinated indenture proposed to
be executed between the Company and Citibank, N.A., as Trustee (the
"Subordinated Indenture"), the form of which is filed as an exhibit to the
Registration Statement, (iii) shares of common stock of the Company, par value
$.01 per share (the "Common Stock"), (iv) shares of preferred stock of the
Company (the "Preferred Stock"), (v) securities issued by each Trust in the form
of trust preferred securities (the "Trust Preferred Securities"), which are
proposed to be issued under the applicable declaration of trust pursuant to
which such Trust is organized (each, as amended and restated prior to such
issuance, in the form of which is filed as an exhibit to the Registration
Statement, a "Declaration of Trust"), (vi) guarantees by the Company of the
Trust Preferred Securities (the "Trust Guarantees") pursuant to a guarantee
agreement (each, a "Trust Guarantee Agreement"), the form of which is filed as
an exhibit to the Registration Statement, (vii ) debt securities of Finance
Company (the "Finance Debt Securities"), which are to be issued under an
indenture between Finance Company and Citibank, N.A., as Trustee (the "Finance
Indenture"), the form of which is incorporated by reference as an exhibit to the
Registration Statement and (viii) guarantees of the Company of the Finance Debt
Securities (the "Finance Guarantees") pursuant to a guarantee agreement (the
"Finance Guarantee Agreement"), the form of which is incorporated by reference
as an exhibit to the Registration Statement. The Senior Debt Securities, the
Subordinated Debt Securities, the Common Stock, the Preferred Stock, the Trust
Preferred Securities, the Trust Guarantees, the Finance Debt Securities and the
Finance Guarantees are referred to collectively as the "Securities" and
individually as a "Security".

                  In connection with this opinion, we have examined originals or
copies, certified or otherwise identified to our satisfaction, of such corporate
records, documents, certificates and instruments as we deemed necessary and
appropriate to enable us to render the opinion expressed below.

                  In our examination, we have assumed (a) the authenticity of
original documents and the genuineness of all signatures, (b) the conformity to
the originals of all documents submitted to us as copies, (c) the truth,
accuracy and completeness of the information, representations and warranties
contained in the records, documents, instruments and certificates we have
reviewed and (d) the due authorization, execution and delivery of each document
named below by each party other than the Company.
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                  We advise you that, in our opinion:

                  (a) With respect to the shares of Common Stock, when (i) the
         Registration Statement, as finally amended (including all necessary
         post-effective amendments), has become effective under the Act; (ii) an
         appropriate prospectus supplement or term sheet with respect to the
         Common Stock has been prepared, delivered and filed in compliance with
         the Act and the applicable rules and regulations promulgated
         thereunder; (iii) if the Common Stock is to be sold pursuant to a firm
         commitment underwritten offering, an underwriting agreement with
         respect to the Common Stock has been duly authorized, executed and
         delivered by the Company and the other parties thereto; (iv) the Board
         of Directors, including any appropriate committee appointed thereby,
         and appropriate officers of the Company have taken all necessary
         corporate action to approve the issuance of the Common Stock and
         related matters; (v) the terms of the issuance and sale of the Common
         Stock have been duly established in conformity with the Certificate of
         Incorporation and the By-laws of the Company so as not to violate any
         applicable law, the Certificate of Incorporation or the By-laws of the
         Company or result in default under or breach of any agreement or
         instrument binding upon the Company and so as to comply with any
         requirement or restriction imposed by any court or governmental body
         having jurisdiction over the Company; and (vi) certificates
         representing the shares of Common Stock have been duly executed,
         countersigned, registered and delivered upon payment of the agreed-upon
         consideration therefor (provided that such consideration is not less
         than the par value thereof), the shares of Common Stock (including any
         Common Stock duly issued upon conversion of any other Security), when
         issued and sold in accordance with the applicable underwriting
         agreement or any other duly authorized, executed and delivered valid
         and binding purchase or agency agreement, will be duly authorized,
         validly issued, fully paid and nonassessable.

                  (b) With respect to the shares of Preferred Stock, when (i)
         the Registration Statement, as finally amended (including all necessary
         post-effective amendments), has become effective under the Act; (ii) an
         appropriate prospectus supplement or term sheet with respect to the
         Preferred Stock has been prepared, delivered and filed in compliance
         with the Act and the applicable rules and regulations promulgated
         thereunder; (iii) if the Preferred Stock is to be sold pursuant to a
         firm commitment underwritten offering, an underwriting agreement with
         respect to the Preferred Stock has been duly authorized, executed and
         delivered by the Company and the other parties thereto; (iv) the Board
         of Directors, including any appropriate committee appointed thereby,
         and appropriate officers of the Company have taken all necessary
         corporate action to approve the issuance and terms of the Preferred
         Stock and related matters, including the adoption of a Certificate of
         Designation for the Preferred Stock in accordance with the applicable
         provisions of Delaware law (the "Certificate of Designation"); (v) the
         filing of the Certificate of Designation with the Secretary of State of
         the State of Delaware has duly occurred; (vi) the terms of the
         Preferred Stock and of their issuance and sale have been duly
         established in conformity with the Company's Certificate of
         Incorporation, including the Certificate of Designation related to the
         Preferred Stock, and the By-laws of the Company so as not to violate
         any applicable law, the Certificate of Incorporation or the By-laws of
         the Company or result in default under or breach of
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         any agreement or instrument binding upon the Company and so as to
         comply with any requirement or restriction imposed by any court or
         governmental body having jurisdiction over the Company; and (vii)
         certificates representing the shares of Preferred Stock have been duly
         executed, countersigned, registered and delivered upon payment of the
         agreed-upon consideration therefor (provided that such consideration is
         not less than the par value thereof), the shares of Preferred Stock
         (including any Preferred Stock duly issued upon conversion of any other
         Security), when issued and sold in accordance with the applicable
         underwriting agreement or any other duly authorized, executed and
         delivered valid and binding purchase or agency agreement, will be duly
         authorized, validly issued, fully paid and nonassessable.

                  (c) With respect to the Senior Debt Securities, when (i) the
         Registration Statement, as finally amended (including all necessary
         post-effective amendments), has become effective under the Act; (ii)
         the Senior Indenture has been duly authorized, executed and delivered
         by the Company and the other parties thereto and duly qualified under
         the Trust Indenture Act of 1939, as amended (the "TIA"); (iii) an
         appropriate prospectus supplement or term sheet with respect to the
         Senior Debt Securities has been prepared, delivered and filed in
         compliance with the Act and the applicable rules and regulations
         promulgated thereunder; (iv) if the Senior Debt Securities are to be
         sold pursuant to a firm commitment underwritten offering, an
         underwriting agreement with respect to the Senior Debt Securities has
         been duly authorized, executed and delivered by the Company and the
         other parties thereto; (v) the Board of Directors, including any
         appropriate committee appointed thereby, and appropriate officers of
         the Company have taken all necessary corporate action to approve the
         issuance and terms of the Senior Debt Securities and related matters;
         (vi) the terms of the Senior Debt Securities and their issuance and
         sale have been duly established in conformity with the Senior Indenture
         so as not to violate any applicable law, the Certificate of
         Incorporation or the By-laws of the Company or result in default under
         or breach of any agreement or instrument binding upon the Company and
         so as to comply with any requirement or restriction imposed by any
         court or governmental body having jurisdiction over the Company; and
         (vii) the Senior Debt Securities have been duly executed and
         authenticated in accordance with the provisions of the Senior Indenture
         and duly delivered to the purchasers thereof upon payment of the
         agreed-upon consideration therefor, the Senior Debt Securities, when
         issued and sold in accordance with the provisions of the Senior
         Indenture and in accordance with the applicable underwriting agreement,
         if any, or any other duly authorized, executed and delivered valid and
         binding purchase or agency agreement, will constitute valid and binding
         obligations of the Company enforceable against the Company in
         accordance with their terms, except as enforcement thereof may be
         limited by (a) bankruptcy, insolvency, reorganization, fraudulent
         conveyance or transfer, moratorium or other laws now or hereafter in
         effect related to or affecting creditors' rights generally and (b)
         general principles of equity (regardless of whether enforceability is
         considered in a proceeding at law or in equity).

                  (d) With respect to the Subordinated Debt Securities, when (i)
         the Registration Statement, as finally amended (including all necessary
         post-effective amendments), has become effective under the Act; (ii)
         the Subordinated Indenture has been duly authorized, executed and
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         delivered by the Company and the other parties thereto and duly
         qualified under the TIA; (iii) an appropriate prospectus supplement or
         term sheet with respect to the Subordinated Debt Securities has been
         prepared, delivered and filed in compliance with the Act and the
         applicable rules and regulations promulgated thereunder; (iv) if the
         Subordinated Debt Securities are to be sold pursuant to a firm
         commitment underwritten offering, an underwriting agreement with
         respect to the Subordinated Debt Securities has been duly authorized,
         executed and delivered by the Company and the other parties thereto;
         (v) the Board of Directors, including any appropriate committee
         appointed thereby, and appropriate officers of the Company have taken
         all necessary corporate action to approve the issuance and terms of the
         Subordinated Debt Securities and related matters; (vi) the terms of the
         Subordinated Debt Securities and their issuance and sale have been duly
         established in conformity with the Subordinated Indenture so as not to
         violate any applicable law, the Certificate of Incorporation or the
         By-laws of the Company or result in default under or breach of any
         agreement or instrument binding upon the Company and so as to comply
         with any requirement or restriction imposed by any court or
         governmental body having jurisdiction over the Company; and (vii) the
         Subordinated Debt Securities have been duly executed and authenticated
         in accordance with the provisions of the Subordinated Indenture and
         duly delivered to the purchasers thereof upon payment of the
         agreed-upon consideration therefor, the Subordinated Debt Securities,
         when issued and sold in accordance with the provisions of the
         Subordinated Indenture and in accordance with the applicable
         underwriting agreement, if any, or any other duly authorized, executed
         and delivered valid and binding purchase or agency agreement, will
         constitute valid and binding obligations of the Company enforceable
         against the Company in accordance with their terms, except as
         enforcement thereof may be limited by (a) bankruptcy, insolvency,
         reorganization, fraudulent conveyance or transfer, moratorium or other
         laws now or hereafter in effect related to or affecting creditors'
         rights generally and (b) general principles of equity (regardless of
         whether enforceability is considered in a proceeding at law or in
         equity).

                  (e) With respect to the Finance Debt Securities, when (i) the
         Registration Statement, as finally amended (including all necessary
         post-effective amendments), has become effective under the Act; (ii)
         the Finance Indenture has been duly qualified under the TIA; (iii) an
         appropriate prospectus supplement or term sheet with respect to the
         Finance Debt Securities has been prepared, delivered and filed in
         compliance with the Act and the applicable rules and regulations
         promulgated thereunder; (iv) if the Finance Debt Securities are to be
         sold pursuant to a firm commitment underwritten offering, an
         underwriting agreement with respect to the Finance Debt Securities has
         been duly authorized, executed and delivered by Finance Company and the
         other parties thereto; (v) the Board of Directors of Finance Company,
         including any appropriate committee appointed thereby, and appropriate
         officers of Finance Company have taken all necessary action to approve
         the issuance and terms of the Finance Debt Securities and related
         matters; (vi) the terms of the Finance Debt Securities and their
         issuance and sale have been duly established in conformity with the
         Finance Indenture so as not to violate any applicable law, the
         Memorandum of Association or the Articles of Association of Finance
         Company or result in default under or breach of any agreement or
         instrument binding upon Finance Company and so as to comply with any
         requirement or restriction imposed by any court or governmental body
         having jurisdiction
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         over Finance Company; and (vii) the Finance Debt Securities have been
         duly executed and authenticated in accordance with the provisions of
         the Finance Indenture and duly delivered to the purchasers thereof upon
         payment of the agreed-upon consideration therefor, the Finance Debt
         Securities, when issued and sold in accordance with the provisions of
         the Finance Indenture and in accordance with the applicable
         underwriting agreement, if any, or any other duly authorized, executed
         and delivered valid and binding purchase or agency agreement, will
         constitute valid and binding obligations of Finance Company enforceable
         against Finance Company in accordance with their terms, except as
         enforcement thereof may be limited by (a) bankruptcy, insolvency,
         reorganization, fraudulent conveyance or transfer, moratorium or other
         laws now or hereafter in effect related to or affecting creditors'
         rights generally and (b) general principles of equity (regardless of
         whether enforceability is considered in a proceeding at law or in
         equity).

                  (f) With respect to the Finance Guarantees, when (i) the
         Registration Statement, as finally amended (including all necessary
         post-effective amendments), has become effective under the Act; (ii)
         the Finance Guarantee Agreement has been duly qualified under the TIA;
         (iii) an appropriate prospectus supplement or term sheet with respect
         to the Finance Debt Securities and the Finance Guarantees has been
         prepared, delivered and filed in compliance with the Act and the
         applicable rules and regulations promulgated thereunder; (iv) the terms
         of the Finance Debt Securities have been established in accordance with
         the Finance Indenture; (v) the Finance Debt Securities have been duly
         issued and executed in accordance with the Finance Indenture and paid
         for in the manner contemplated in the Registration Statement or any
         prospectus relating thereto; (vi) if the Finance Debt Securities and
         Finance Guarantees are to be sold pursuant to a firm commitment
         underwritten offering, an underwriting agreement with respect to such
         Securities has been duly authorized, executed and delivered by Finance
         Company and the other parties thereto; (vii) the Board of Directors,
         including any appropriate committee appointed thereby, and appropriate
         officers of the Company have taken all necessary corporate action to
         approve the issuance and terms of the Finance Guarantees and related
         matters; (viii) the terms of the Finance Guarantees and of their
         issuance and sale have been duly established in conformity with the
         Finance Guarantee Agreement so as not to violate any applicable law,
         the Certificate of Incorporation or the By-laws of the Company or
         result in default under or breach of any agreement or instrument
         binding upon the Company and so as to comply with any requirement or
         restriction imposed by any court or governmental body having
         jurisdiction over the Company; and (ix) the Finance Guarantees have
         been duly executed and delivered in accordance with the provisions of
         the Finance Guarantee Agreement, the Finance Guarantees, when issued in
         accordance with the Finance Guarantee Agreement, will constitute valid
         and binding obligations of the Company enforceable against the Company
         in accordance with their terms, except as enforcement thereof may be
         limited by (a) bankruptcy, insolvency, reorganization, fraudulent
         conveyance or transfer, moratorium or other laws now or hereafter in
         effect related to or affecting creditors' rights generally and (b)
         general principles of equity (regardless of whether enforceability is
         considered in a proceeding at law or in equity).
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                  (g) With respect to the Trust Guarantees, when (i) the
         Registration Statement, as finally amended (including all necessary
         post-effective amendments), has become effective under the Act; (ii)
         the applicable Trust Guarantee Agreement has been duly authorized,
         executed and delivered by the Company and the other parties thereto and
         duly qualified under the TIA; (iii) an appropriate prospectus
         supplement or term sheet with respect to the Trust Preferred Securities
         and the Trust Guarantees has been prepared, delivered and filed in
         compliance with the Act and the applicable rules and regulations
         promulgated thereunder; (iv) the Declaration of Trust of the applicable
         Trust has been duly authorized, executed and delivered by the parties
         thereto; (v) the terms of the Trust Preferred Securities have been
         established in accordance with the applicable Declaration of Trust;
         (vi) the Trust Preferred Securities have been duly issued and executed
         in accordance with the applicable Declaration of Trust and paid for in
         the manner contemplated in the Registration Statement or any prospectus
         relating thereto; (vii) if the Trust Preferred Securities and the Trust
         Guarantees are to be sold pursuant to a firm commitment underwritten
         offering, an underwriting agreement with respect to such Securities has
         been duly authorized, executed and delivered by the applicable Trust
         and the other parties thereto; (viii) the Board of Directors, including
         any appropriate committee appointed thereby, and appropriate officers
         of the Company have taken all necessary corporate action to approve the
         issuance and terms of the Trust Guarantees and related matters; (ix)
         the terms of the Trust Guarantees and of their issuance and sale have
         been duly established in conformity with the applicable Trust Guarantee
         Agreement so as not to violate any applicable law, the Certificate of
         Incorporation or the By-laws of the Company or result in default under
         or breach of any agreement or instrument binding upon the Company and
         so as to comply with any requirement or restriction imposed by any
         court or governmental body having jurisdiction over the Company; and
         (x) the Trust Guarantees have been duly executed and delivered in
         accordance with the provisions of the applicable Trust Guarantee
         Agreement, the Trust Guarantees, when issued in accordance with the
         applicable Trust Guarantee Agreement, will constitute valid and binding
         obligations of the Company enforceable against the Company in
         accordance with their terms, except as enforcement thereof may be
         limited by (a) bankruptcy, insolvency, reorganization, fraudulent
         conveyance or transfer, moratorium or other laws now or hereafter in
         effect related to or affecting creditors' rights generally and (b)
         general principles of equity (regardless of whether enforceability is
         considered in a proceeding at law or in equity).

                  In rendering the opinion set forth above, we express no
opinion as to the laws of any jurisdiction other than the laws of the State of
New York, the General Corporation law of the State of Delaware, including the
applicable provisions of the Delaware Constitution and the reported judicial
decisions interpreting the laws, and the federal laws of the United States of
America. The Securities may be issued from time to time on a delayed or
continuous basis, and our opinion is limited to the laws as in effect on the
date hereof.

                  With respect to opinions (e) and (f) above, we have relied on
the opinion of Stewart McKelvey Stirling Scales dated as of the date hereof, as
to the due organization and valid existence of the Finance Company. With respect
to opinion (g) above, we have relied on the opinion of Richards,
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Layton & Finger, P.A., dated as of the date hereof, as to the Trusts and the
validity and legality of the Trust Preferred Securities and related documents
(other than the Trust Guarantees).

                  We hereby consent to the incorporation by reference of this
opinion as an exhibit to the Registration Statement and to the reference of our
firm under the caption "Legal Matters" in the Registration Statement and the
prospectus forming a part thereof. Our consent to such reference does not
constitute a consent under Section 7 of the Act, as in consenting to such
reference we have not certified any part of the Registration Statement and do
not otherwise come within the categories of persons whose consent is required
under Section 7 or under the rules and regulations of the Securities and
Exchange Commission thereunder.

                                             Very truly yours,

                                             /s/ Cahill Gordon & Reindel

                                             Cahill Gordon & Reindel