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                                                                    EXHIBIT 5(b)


                                                     December 15, 2000


CMS Energy Corporation
CMS Energy Trust IV
CMS Energy Trust V
c/o CMS Energy Corporation
Fairlane Plaza South, Suite 1100
330 Town Center Drive
Dearborn, Michigan  48126

                 Re:  CMS Energy Corporation
                      CMS Energy Trust  IV
                      CMS Energy Trust V
                      Registration Statement on Form S-3

Dear Ladies and Gentlemen:

                  We have acted as special counsel to CMS Energy Trust IV and
CMS Energy Trust V (each a "CMS Trust" and, together, the "CMS Trusts"), each a
statutory business trust formed under the Business Trust Act of the State of
Delaware, in connection with the preparation of a Registration Statement on
Form S-3 (the "Registration Statement"), to be filed by CMS Energy Corporation,
a Michigan corporation (the "Company") and the CMS Trusts with the Securities
and Exchange Commission (the "Commission") on December 15, 2000 under the
Securities Act of 1933, as amended (the "Act"). The Registration Statement
relates to, among other things, the issuance and sale from time to time pursuant
to Rule 415 of the General Rules and Regulations promulgated under the Act, of
the trust preferred securities (the "Preferred Securities") of each of the CMS
Trusts.

                  The Preferred Securities of each CMS Trust are to be issued
pursuant to the Amended and Restated Trust Agreement of such CMS Trust (each a
"Trust Agreement" and, collectively, the "Trust Agreements"), each such Trust
Agreement being among the Company, as sponsor, The Bank of New York as property
trustee



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CMS Energy Corporation
CMS Energy Trust IV
CMS Energy Trust V
December 15, 2000
Page 2




(the "Property Trustee"), The Bank of New York (Delaware), as Delaware trustee
and Alan M. Wright and Thomas A. McNish, as administrative trustees.

                  This opinion is being delivered in accordance with the
requirements of Item 601(b)(5) of Regulation S-K under the Act.

                  In connection with this opinion, we have examined originals or
copies, certified or otherwise identified to our satisfaction, of (i) the
certificates of trust of each of the CMS Trusts (the "Certificates of Trust") as
filed with the Secretary of State of the State of Delaware on December 1, 2000
(ii) the form of the Trust Agreement of each of the CMS Trusts (including the
designation of the terms of the Preferred Securities annexed thereto); and (iii)
the form of the Preferred Securities of each of the CMS Trusts. We have also
examined originals or copies, certified or otherwise identified to our
satisfaction, of such other documents, certificates and records as we have
deemed necessary or appropriate as a basis for the opinions set forth herein.

                  In our examination, we have assumed the legal capacity of all
natural persons, the genuineness of all signatures, the authenticity of all
documents submitted to us as originals, the conformity to original documents of
all documents submitted to us as certified, photostatic or facsimile copies and
the authenticity of the originals of such latter documents. In making our
examination of executed documents or documents to be executed, we have assumed
that the parties thereto, other than the CMS Trusts, had or will have the power,
corporate or other, to enter into and perform all obligations thereunder and
have also assumed the due authorization by all requisite action, corporate or
other, and execution and delivery by such parties of such documents and the
validity and binding effect thereof. In addition, we have also assumed that the
Trust Agreement of each CMS Trust, and the Preferred Securities of each CMS
Trust, when executed, will be in substantially the form reviewed by us and that
the terms of the Preferred Securities will have been established so as not to
violate, conflict with or constitute a default under (i) any agreement or
instrument to which the Company or any of the CMS Trusts or their respective
property is subject, (ii) any law, rule, or regulation to which the Company or
any of the CMS Trusts is


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CMS Energy Corporation
CMS Energy Trust IV
CMS Energy Trust V
December 15, 2000
Page 3



subject, (iii) any judicial or administrative order or decree of any
governmental authority or (iv) any consent, approval, license, authorization or
validation of, or filing, recording or registration with any governmental
authority. As to any facts material to the opinions expressed herein which we
did not independently establish or verify, we have relied upon oral or written
statements and representations of officers and other representatives of the
Company, the CMS Trusts and others.

                  We do not express any opinion as to the laws of any
jurisdiction other than the Business Trust Act of the State of Delaware.

                  Based on and subject to the foregoing and to the other
qualifications and limitations set forth herein, we are of the opinion that the
Preferred Securities of each CMS Trust to be offered pursuant to the
Registration Statement (the "Offered Preferred Securities"), when (i) the
Registration Statement, as finally amended (including all necessary
post-effective amendments), has become effective under the Act; (ii) an
appropriate prospectus with respect to the Offered Preferred Securities has been
prepared, delivered and filed in compliance with the Act and the applicable
rules and regulations thereunder; (iii) the Trust Agreement of such CMS Trust
has been duly executed and delivered by the parties thereto; (iv) the terms of
the Offered Preferred Securities have been established in accordance with the
Trust Agreement; (v) the Offered Preferred Securities have been issued, executed
and authenticated in accordance with the Trust Agreement and delivered and paid
for in the manner contemplated in the Registration Statement or any prospectus
relating thereto; and (vi) if the Offered Preferred Securities are to be sold
pursuant to a firm commitment underwritten offering, the underwriting agreement
with respect to the Offered Preferred Securities has been duly authorized,
executed and delivered by the applicable CMS Trust and the other parties
thereto, the Offered Preferred Securities will be duly authorized for issuance
and will be validly issued, fully paid and nonassessable, representing undivided
beneficial interests in the assets of such CMS Trust. We bring to your
attention, however, that the holders of the Offered Preferred Securities may be
obligated, pursuant to the Trust Agreement of such CMS Trust, to (i) provide
indemnity and/or security in connection with, and pay taxes or governmental
charges arising from, transfers of Offered Preferred Securities and (ii) provide
security and


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CMS Energy Corporation
CMS Energy Trust IV
CMS Energy Trust V
December 15, 2000
Page 4


indemnity in connection with the requests of or directions to the Property
Trustee of such CMS Trust to exercise its rights and powers under the Trust
Agreement of such CMS Trust.

                  We hereby consent to the filing of this opinion with the
Commission as an exhibit to the Registration Statement. We also consent to the
use of our name under the heading "Legal Opinions" in the base prospectus
included in the Registration Statement. In giving this consent, we do not
hereby admit that we are within the category of persons whose consent is
required under Section 7 of the Act or the rules and regulations of the
Commission promulgated thereunder. This opinion is expressed as of the date
hereof unless otherwise expressly stated and we disclaim any undertaking to
advise you of any subsequent changes of the facts stated or assumed herein or of
any subsequent changes in applicable law.

                                       Very truly yours,


                                       /s/ Skadden, Arps, Slate, Meagher
                                           & Flom LLP