Exhibit 5.1
 
                      [Letterhead of John R. Light, Esq.]
 
                                  May 5, 1999
 
Sempra Energy
101 Ash Street
San Diego, CA 92101
 
  Re: Registration Statement on Form S-3 of Sempra Energy, Sempra Holdings,
     Inc., Sempra Energy Capital Trust I, Sempra Energy Capital Trust II and
     Sempra Energy Capital Trust III
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Ladies and Gentlemen:
 
  I am the Executive Vice President and General Counsel of Sempra Energy, a
California corporation. In connection with the registration statement on Form
S-3 filed on May 5, 1999 (the "Registration Statement") by Sempra Energy, a
California Corporation, Sempra Holdings, a California corporation, Sempra
Energy Capital Trust I, a Delaware Trust, Sempra Energy Capital Trust II, a
Delaware Trust, and Sempra Energy Capital Trust III, a Delaware Trust
(collectively, the "Registrants") with the Securities and Exchange Commission
(the "Commission") under the Securities Act of 1933, as amended (the
"Securities Act"), you have requested my opinion with respect to the matters
set forth below.
 
  I have reviewed the prospectus (the "Prospectus") which is a part of the
Registration Statement. The Prospectus provides that it will be supplemented in
the future by one or more supplements to the Prospectus (each a "Prospectus
Supplement"). The Prospectus as supplemented by various Prospectus Supplements
will provide for the registration of up to $1,000,000,000 aggregate offering
price of (i) one or more series of unsecured senior or subordinated debt
securities (the "Debt Securities") which may be issued by Sempra Energy or
Sempra Energy Holdings, (ii) shares of common stock, without par value, which
may be issued by Sempra Energy (the "Common Stock"), (iii) shares of preferred
stock, without par value, which may be issued by Sempra Energy (the "Preferred
Stock"), (iv) preferred securities (the "Preferred Securities") which may be
issued by each Trust pursuant to their respective Amended and Restated
Declarations of Trust (each an "Amended Declaration") and (v) guarantees of the
Preferred Securities, which may be issued by Sempra Energy (the "Preferred
Securities Guarantees"), and the Debt Securities issued by Sempra Energy
Holdings (the "Debt Securities Guarantees" and, together with the Preferred
Securities Guarantees, the "Guarantees") described below pursuant to one or
more guarantee agreements (each a "Guarantee Agreement"). The Debt Securities,
the Guarantees and the Common and Preferred Stock are collectively referred to
herein as the "Securities." Any Debt Securities may be exchangeable and/or
convertible into shares of Common Stock. The Debt Securities may be issued
pursuant to one or more indentures and one or more supplements thereto
(collectively, the "Indentures"), in each case between Sempra Energy or Sempra
Holdings and a trustee (each, a "Trustee").

 
  In my capacity as General Counsel, I am generally familiar with the
proceedings taken and proposed to be taken by the Registrants in connection
with the authorization and issuance of the Securities. For purposes of this
opinion, I have assumed that such proceedings will be timely and properly
completed, in accordance with all requirements of applicable federal, Delaware,
California and New York laws, in the manner presently proposed.
 
  I have made such legal and factual examinations and inquiries, including an
examination of originals and copies certified or otherwise identified to my
satisfaction, of all such documents, corporation records and instruments of the
Registrants as I have deemed necessary or appropriate for purposes of this
opinion. In my examination, I have assumed the genuineness of all signatures,
the authenticity of all documents submitted to me as originals, and the
conformity to authentic original documents of all documents submitted to me as
copies.
 
  I have been furnished with, and with your consent have exclusively relied
upon, certificates of officers of Sempra Energy with respect to certain factual
matters. In addition, I have obtained and relied upon such certificates and
assurances from public officials as I have deemed necessary.
 
  I am opining herein as to the effect on the subject transaction only of the
federal securities laws of the United States, the General Corporation Law of
the State of Delaware and the State of California and with respect to opinion
paragraphs 1, 2 and 3 below, the internal laws of the State of New York, and I
express no opinion with respect to the applicability thereto, or the effect
thereon, of the laws of any other jurisdiction or, in the case of Delaware and
California, any other laws, or as to any matters of municipal law or the laws
of any local agencies within any state.
 
  Subject to the foregoing and the other qualifications set forth herein, it is
my opinion that, as of the date hereof:
 
  1. When (a) the Debt Securities have been duly established in accordance with
the terms of the applicable Indentures (including, without limitation, the
adoption by the Board of Directors of Sempra Energy and/or Sempra Energy
Holdings of any necessary further resolutions duly authorizing the issuance and
delivery of the Debt Securities), duly authenticated by the Trustee and duly
executed and delivered on behalf of Sempra Energy and/or Sempra Energy Holdings
against payment therefor in accordance with the terms and provisions of the
applicable Indenture and as contemplated by the Registration Statement, the
Prospectus and the related Prospectus Supplement(s), and (b) when each of the
Registration Statement and any required post-effective amendment thereto have
all become effective under the Securities Act and (c) assuming that the terms
of the Debt Securities as executed and delivered are as described in the
Registration Statement, the Prospectus and the related prospectus
Supplement(s), and (d) assuming that the Debt Securities as executed and
delivered do not violate any law applicable to the issuing company or result in
a default under or breach of any agreement or instrument binding upon the
issuing company, and (e) assuming that the Debt Securities as executed and
delivered comply with all requirements and restrictions, if any, applicable to
the issuing company, whether imposed by any court or governmental or regulatory
body having jurisdiction over the issuing company, and (f) assuming that the
Debt Securities are then issued and sold as contemplated in the Registration
Statement, the Prospectus and the related Prospectus Supplement(s), the Debt
Securities will constitute valid and legally binding obligations of the issuing
company enforceable against the issuing company in accordance with the terms of
the Debt Securities.

 
  2. When (a) the Debt Securities Guarantees and the related Debt Securities
have been duly established in accordance with the terms of the applicable
Indentures (including, without limitation, the adoption by the Board of
Directors of Sempra Energy of any necessary further resolutions duly
authorizing the issuance and delivery of the Debt Securities Guarantees and the
related Debt Securities), the Debt Securities Guarantees have been duly
executed and delivered and the related Debt Securities have been authenticated
by the Trustee and duly executed and delivered on behalf of Sempra Energy
against payment therefor in accordance with the terms and provisions of the
applicable Indenture and as contemplated by the Registration Statement, the
Prospectus and the related Prospectus Supplement(s), and (b) when each of the
Registration Statement and any required post-effective amendment thereto have
all become effective under the Securities Act, and (c) assuming that the terms
of the Debt Securities Guarantees as executed and delivered are as described in
the Registration Statement, the Prospectus and the related Prospectus
Supplement(s), and (d) assuming that the Debt Securities Guarantees as executed
and delivered do not violate any law applicable to Sempra Energy or result in a
default under or breach of any agreement or instrument binding upon Sempra
Energy, and (e) assuming that the Debt Securities Guarantees as executed and
delivered comply with all requirements and restrictions, if any, applicable to
Sempra Energy, whether imposed by any court or governmental or regulatory body
having jurisdiction over Sempra Energy, and (f) assuming that the Debt
Securities Guarantees are then issued as contemplated in the Registration
Statement, the Prospectus and the related Prospectus Supplement(s), the Debt
Securities Guarantees will constitute valid and legally binding obligations of
Sempra Energy, enforceable against Sempra Energy in accordance with the terms
of the Debt Securities Guarantees.
 
  3. With respect to the Preferred Securities Guarantees, when (i) the trustees
of the applicable Trust have taken all necessary action to adopt the Amended
Declaration and to fix and determine the terms of the applicable Preferred
Securities in accordance with the terms of the applicable Amendment
Declaration; (ii) the appropriate officers of Sempra Energy have taken all
necessary action to fix and determine the terms of the applicable Preferred
Securities Guarantees in accordance with the resolutions adopted by the Board
of Directors of Sempra Energy relating to the issuance and delivery of the
Preferred Securities; (iii) the terms of the applicable Preferred Securities
and the related Preferred Securities Guarantee and the issuance and sale
thereof have been duly established in conformity with the applicable amended
Declaration and applicable Guarantee Agreement, respectively, so as not to
violate any applicable law, the applicable Certificate of Trust, Declaration of
Trust and Amended Declaration, and the Articles of Incorporation and By-laws of
Sempra Energy, or result in a default under or breach of any agreement or
instrument binding upon the applicable Trust or Sempra Energy; (iv) the
applicable Guarantee Agreement has been duly executed and delivered; (v) the
applicable Preferred Securities have been duly issued and delivered by the
applicable Trust as contemplated by the Registration Statement and the
prospectus supplement relating thereto; (vi) certificates representing the
applicable Preferred Securities have been manually authenticated by an
authorized officer of the applicable Property Trustee (as defined in the
applicable Amended Declaration) for the applicable Preferred Securities and
registered by such Property Trustee and delivered to the purchasers thereof;
(vii) the applicable Trust receives the agreed-upon consideration therefor and
(viii) the applicable Guarantee Agreement shall have been qualified under the
Trust Indenture Act of 1939, as amended, the applicable Preferred Securities
Guarantee will be a valid and binding obligation of Sempra Energy enforceable
in accordance with its terms.
 
  4. Sempra Energy has the authority pursuant to its Articles of Incorporation
to issue up to 750,000,000 shares of Common Stock and 50,000,000 shares of
Preferred Stock. Upon adoption by the Board of Directors of Sempra Energy of
any necessary further resolutions in form and content as required by applicable
law and upon issuance and delivery of and payment for such shares in the

 
manner contemplated by the Registration Statement, the Prospectus and the
related Prospectus Supplement(s) and by such resolution, such shares of common
Stock (including any Common Stock duly issued upon the exchange or conversion
of Debt Securities that are exchangeable or convertible into Common Stock) or
Preferred Stock will be validly issued, fully paid and nonassessable.
 
  The opinions set forth in paragraphs 1 through 4 above are subject to the
following exceptions, limitations and qualifications: (i) the effect of
bankruptcy, insolvency, reorganization, moratorium or other similar laws now or
hereafter in effect relating to or affecting the rights and remedies of
creditors; (ii) the effect of general principles of equity, including without
limitation, concepts of materiality, reasonableness, good faith and fair
dealing and the possible unavailability of specific performance or injunctive
relief, regardless of whether enforcement is considered in a proceeding in
equity or at law, and the discretion of the court before which any proceeding
therefor may be brought; (iii) the unenforceability under certain circumstances
under law or court decisions of provisions providing for the indemnification
of, or contribution to, a party with respect to a liability where such
indemnification or contribution is contrary to public policy; (iv) requirements
that a claim with respect to any Guarantee denominated other than in United
States dollars (or a judgment denominated other than in United States dollars
in respect of such claim) be converted into United States dollars at a rate of
exchange prevailing on a date determined pursuant to applicable law;
(v) governmental authority to limit, delay or prohibit the making of payments
outside the United States or in a foreign currency, composite currency or
current unit; (vi) I express no opinion concerning the enforceability of any
waiver of rights or defenses with respect to stay, extension or usury laws; and
(vii) I express no opinion with respect to whether acceleration of Debt
Securities may affect the collectibility of any portion of the stated principle
amount thereof which might be determined to constitute unearned interest
thereon.
 
  I have assumed for purposes of this opinion that the applicable Indenture
constitutes the legally valid, binding and enforceable obligation of each of
Sempra Energy and Sempra Energy Holdings enforceable against each of Sempra
Energy and Sempra Energy Holdings in accordance with its terms; and that
Trustee for each Indenture is duly organized, validly existing and in good
standing under the laws of its jurisdiction of organization; that the Trustee
is duly qualified to engage in the activities contemplated by the applicable
Indenture; that the applicable Indenture has been duly authorized, executed and
delivered by the Trustee and constitutes a legally valid, binding and
enforceable obligation of the Trustee, enforceable against the Trustee in
accordance with its terms; and the Trustee is in compliance, generally and with
respect to acting as Trustee under the applicable Indenture, with all
applicable laws and regulations; and that the Trustee has the requisite
organizational and legal power and authority to perform its obligations under
the applicable Indenture.
 
  I consent to your filling this opinion as an exhibit to the Registration
Statement and to the reference to me under the caption "Validity of the
Securities and the Guarantees" in the Prospectus included therein.
 
                                          Very truly yours,
 
                                          /s/ John R. Light
                                          -------------------------------------
                                          John R. Light, Esq.
                                          Executive Vice President and General
                                           Counsel