EXHIBIT 5a

[CMS ENERGY ENTERPRISES LOGO]

- --------------------------------------------------------------------------------
                                                             ROBERT C. SHROSBREE
                                                       Assistant General Counsel




                                  June 3, 2005


CMS Energy Corporation
One Energy Plaza
Jackson, MI 49201

Ladies and Gentlemen:

         I am the Assistant General Counsel of CMS Energy Corporation, a
Michigan corporation ("CMS Energy" or the "Company"), and have acted as such in
connection with the Registration Statement on Form S-3 (the "Registration
Statement") being filed by the Company with the Securities and Exchange
Commission (the "Commission") under the Securities Act of 1933, as amended (the
"Securities Act"), relating to the registration of $1,500,000,000 of: (i) CMS
Energy Common Stock, $.01 par value ("CMS Energy Common Stock"); (ii) Senior
Debentures of the Company ("Senior Debentures"); (iii) Subordinated Debentures
of the Company ("Subordinated Debentures"); (iv) Trust Preferred Securities of
CMS Energy Trust IV; (v) Trust Preferred Securities of CMS Energy Trust V; (vi)
Guarantee of CMS Energy Corporation with respect to Trust Preferred Securities
of CMS Energy Trust IV and CMS Energy Trust V; (vii) Stock Purchase Contracts of
the Company; and (viii) Stock Purchase Units of the Company. (The offered
securities, collectively, the "Securities".) The Trust Preferred Securities
Guarantee is to be issued pursuant to a Trust Preferred Securities Guarantee
Agreement (the "Trust Preferred Securities Guarantee Agreement") to be entered
into between the Company and The Bank of New York, as Trustee (the "Guarantee
Trustee"). The Subordinated Debentures are to be issued under an Indenture to be
entered into between the Company and The Bank of New York, as trustee (the
"Subordinated Indenture Trustee"), and one or more supplemental indentures
thereto (collectively, the "Subordinated Indenture"). The Senior Debentures are
to be issued under an Indenture to be entered into between the Company and J.P.
Morgan Trust Company, N.A., as trustee (the "Senior Indenture Trustee"), and one
or more supplemental indentures thereto (collectively the "Senior Indenture").
Capitalized terms not otherwise defined herein have the respective meanings
specified in the Registration Statement.












One Energy Plaza o Jackson, MI 49201-2357 o Tel 517 768 7323 o Fax 517 788 8011







CMS Energy Corporation
June 3, 2005
Page 2


         In rendering this opinion, I have examined and relied upon a copy of
the Registration Statement. I have also examined, or have arranged for the
examination by an attorney or attorneys under my general supervision, originals,
or copies of originals certified to my satisfaction, of such agreements,
documents, certificates and other statements of governmental officials and other
instruments, and have examined such questions of law and have satisfied myself
as to such matters of fact, as I have considered relevant and necessary as a
basis for this opinion. I have assumed the authenticity of all documents
submitted to me as originals, the genuineness of all signatures, the legal
capacity of all natural persons and the conformity with the original documents
of any copies thereof submitted to me for examination.

         I note that the issuance of the Trust Preferred Securities is governed
by the laws of the State of Delaware. Any matters relating to Delaware law will
be opined upon by Skadden, Arps, Slate, Meagher & Flom LLP.

         Based on the foregoing, it is my opinion that:

         1.       The Company is duly incorporated and validly existing under
                  the laws of the State of Michigan.

         2.       The Company has the corporate power and authority: (i) to
                  execute and deliver the Senior Indenture and the Subordinated
                  Indenture and the Trust Preferred Securities Guarantee, and
                  (ii) to authorize and sell the CMS Energy Common Stock, any
                  Stock Purchase Contract or Stock Purchase Unit and the Senior
                  Debentures and the Subordinated Debentures pursuant to the
                  Senior Indenture and the Subordinated Indenture, respectively.

         3.       The Trust Preferred Securities Guarantee will be a legally
                  issued and binding obligation of the Company (except to the
                  extent enforceability may be limited by applicable bankruptcy,
                  insolvency, reorganization, moratorium, fraudulent transfer or
                  other similar laws affecting the enforcement of creditors'
                  rights generally and by the effect of general principles of
                  equity, regardless of whether enforceability is considered in
                  a proceeding in equity or at law) when: (i) the Registration
                  Statement, as finally amended (including any necessary
                  post-effective amendments), shall have become effective under
                  the Securities Act; (ii) the Trust Preferred Securities
                  Guarantee shall have been qualified under the Trust Indenture
                  Act of 1939, as amended (the "Trust Indenture Act"), and duly
                  executed and delivered by the Company and the Guarantee
                  Trustee; (iii) the Trust Preferred Securities shall have been
                  legally issued; and (iv) the Trust Preferred Securities
                  Guarantee shall have been duly executed and delivered as
                  provided in the Trust Preferred Securities Guarantee
                  Agreement.

         4.       The Senior or Subordinated Debentures will be legally issued
                  and binding obligations of the Company (except to the extent
                  enforceability may be limited






CMS Energy Corporation
June 3, 2005
Page 3


                  by applicable bankruptcy, insolvency, reorganization,
                  moratorium, fraudulent transfer or other similar laws
                  affecting the enforcement of creditors' rights generally and
                  by the effect of general principles of equity, regardless of
                  whether enforceability is considered in a proceeding in equity
                  or at law) when: (i) the Registration Statement, as finally
                  amended (including any necessary post-effective amendments),
                  shall have become effective under the Securities Act; (ii) in
                  the case of the Senior Debentures, the Senior Indenture shall
                  have been qualified under the Trust Indenture Act and duly
                  executed and delivered by the Company and the Senior Indenture
                  Trustee and in the case of the Subordinated Debentures, the
                  Subordinated Indenture shall have been qualified under the
                  Trust Indenture Act and duly executed by the Company and the
                  Subordinated Indenture Trustee; (iii) an appropriate
                  prospectus supplement with respect to the particular Senior
                  Debentures or Subordinated Debentures then being sold by the
                  Company shall have been filed with the Commission pursuant to
                  Rule 424 under the Securities Act; (iv) the Company's Board of
                  Directors or duly authorized committee thereof shall have duly
                  adopted final resolutions authorizing the issuance and sale of
                  the particular Senior Debentures or Subordinated Debentures,
                  as contemplated by the Registration Statement and the Senior
                  Indenture or the Subordinated Indenture; (v) the supplemental
                  indenture under which the particular Senior Debentures or
                  Subordinated Debentures are to be issued shall have been duly
                  executed and authenticated as provided in the respective
                  Senior Indenture or Subordinated Indenture and such
                  resolutions; and (vi) the particular Senior Debentures or
                  Subordinated Debentures shall have been duly delivered to the
                  purchasers thereof against payment of the agreed consideration
                  therefor.

         5.       The Stock Purchase Contracts and the Stock Purchase Units,
                  when issued and sold, will be legally issued and binding
                  obligations of the Company (except to the extent
                  enforceability may be limited by applicable bankruptcy,
                  insolvency, reorganization, moratorium, fraudulent transfer or
                  other similar laws affecting the enforcement of creditors'
                  rights generally and by the effect of general principles of
                  equity, regardless of whether enforceability is considered in
                  a proceeding in equity or at law) when: (i) the Registration
                  Statement, as finally amended (including any necessary
                  post-effective amendments), shall have become effective under
                  the Securities Act; (ii) an appropriate prospectus supplement
                  with respect to the particular Stock Purchase Contracts and
                  the particular Stock Purchase Units then being sold by the
                  Company shall have been filed with the Commission pursuant to
                  Rule 424 under the Securities Act; and (iii) the Stock
                  Purchase Contracts under which the CMS Energy Common Stock are
                  to be purchased shall have been duly executed and delivered as
                  provided in the Stock Purchase Contracts.

         6.       The CMS Energy Common Stock will be legally issued, fully paid
                  and non-assessable when: (i) the Registration Statement, as
                  finally amended, shall have become effective under the
                  Securities Act; (ii) an appropriate prospectus







CMS Energy Corporation
June 3, 2005
Page 4


                  supplement with respect to the CMS Energy Common Stock, Trust
                  Preferred Securities or Subordinated Debentures to be
                  converted into CMS Energy Common Stock or Stock Purchase
                  Contracts pursuant to which CMS Energy Common Stock may be
                  purchased, as contemplated by the Registration Statement shall
                  have been filed with the Commission pursuant to Rule 424 under
                  the Securities Act; (iii) the Company's Board of Directors or
                  a duly authorized committee thereof shall have duly adopted
                  final resolutions authorizing the issuance and sale of the CMS
                  Energy Common Stock, Trust Preferred Securities or
                  Subordinated Debentures to be converted into CMS Energy Common
                  Stock or Stock Purchase Contracts pursuant to which CMS Energy
                  Common Stock may be purchased, as contemplated by the
                  Registration Statement and prospectus supplement relating
                  thereto; and (iv) upon delivery, purchase or conversion, as
                  the case may be, certificates representing the CMS Energy
                  Common Stock shall have been duly executed, countersigned and
                  registered and duly delivered to the purchasers thereof
                  against payment of the agreed consideration therefor.

         For purposes of this opinion, I have assumed that there will be no
changes in the laws currently applicable to the Company and that such laws will
be the only laws applicable to the Company.

         I do not find it necessary for the purposes of this opinion to cover,
and accordingly I express no opinion as to, the application of the securities or
blue sky laws of the various states to the execution and delivery of the Trust
Preferred Securities Guarantee or the sale of the Securities.

         I am a member of the bar of the State of Michigan and I express no
opinion as to the laws of any jurisdiction other than the State of Michigan and
the federal law of the United States of America. I note that the rights, duties
and obligations of the Subordinated Indenture Trustee under the Subordinated
Indenture are stated to be governed and construed in accordance with the laws of
the State of New York. However, for purposes of paragraph 4 above, I have
assumed that the Subordinated Indenture, as to the rights, duties and
obligations of the Subordinated Indenture Trustee, is stated to be governed by
the laws of the State of Michigan.

         I hereby consent to the filing of this opinion as an exhibit to the
Company's Registration Statement on Form S-3 relating to the Securities and to
all references to me included in or made a part of the Registration Statement.

                                        Very truly yours,


                                        /s/ Robert C. Shrosbree

                                        ---------------------------
                                        Robert C. Shrosbree