EXHIBIT 5(a)

                  [LETTERHEAD OF CITIZENS BANKING CORPORATION]

                               September 20, 2006

Citizens Banking Corporation
328 South Saginaw Street
Flint, Michigan  48502

         Re:      Citizens Banking Corporation
                  Registration Statement on Form S-3ASR

Dear Sirs:

      I am General Counsel and Secretary of Citizens Banking Corporation, a
Michigan corporation (the "Registrant"), and I have represented the Registrant
in connection with the Registration Statement on Form S-3 (the "Registration
Statement") filed with the Securities and Exchange Commission (the "Commission")
under the Securities Act of 1933, as amended (the "Act"), relating to the
offering from time to time, as set forth in the two prospectuses contained in
the Registration Statement (each, a "Prospectus"), and as to be set forth in one
or more supplements to the Prospectuses (each such supplement, a "Prospectus
Supplement"), of the Registrant's senior debt securities (the "Senior Debt
Securities"), senior subordinated debt securities (the "Senior Subordinated Debt
Securities"), junior subordinated debt securities (the "Junior Subordinated Debt
Securities"), preferred stock (the "Preferred Stock"), depositary shares (the
"Depositary Shares"), common stock (the "Common Stock"), warrants (the
"Warrants"), stock purchase contracts (the "Stock Purchase Contracts"), units
(the Units") and guarantees of preferred securities of certain affiliated trust
entities (collectively, the "Securities"). The Securities being registered under
the Registration Statement will be offered on a continuous or delayed basis
pursuant to Rule 415 under the Act.

      I or members of my staff have examined the originals or copies certified
or otherwise identified to our satisfaction, of the Registration Statement such
corporate records and documents relating to the Registrant, including
resolutions of the Board of Directors of the Registrant authorizing the
issuance, offering and sale of the Securities, have examined such forms of
agreements and indentures and have made such other inquiries of law and fact as
we have deemed necessary or relevant as the basis of my opinion hereinafter
expressed. Certain terms of the Securities to be issued by the Registrant from
time to time will be approved by the Board of Directors of the Registrant or a
duly authorized committee thereof or certain authorized officers of the
Registrant as part of the corporate action taken and to be taken in connection
with issuance of the Securities.

      Based on the foregoing, and subject to the qualifications and limitations
stated herein, I am of the opinion that:

      1.    the Senior Debt Securities to be issued under the indenture (the
            "Senior Debt Indenture") to be entered into between the Registrant
            and U.S. Bank National Association, as trustee (the "Trustee") have




            been duly authorized and, assuming the due authorization of the
            Senior Debt Indenture by the Trustee, (i) when the final terms
            thereof have been duly established and approved, the form of Senior
            Debt Indenture has been finalized and has been duly executed and
            delivered and the Senior Debt Securities have been duly executed by
            the Registrant, in each case pursuant to the authority granted by
            the Board of Directors of the Registrant, (ii) upon the execution
            and delivery by the Registrant and the Trustee and, if required by
            the Senior Debt Indenture, a supplement to the Senior Debt
            Indenture, and (iii) when the Senior Debt Securities have been
            authenticated by the Trustee and issued in accordance with the terms
            of the Senior Debt Indenture and delivered to and paid for by the
            purchasers thereof, the Senior Debt Securities will constitute valid
            and legally binding obligations of the Registrant entitled to the
            benefits of the Senior Debt Indenture;

      2.    the Senior Subordinated Debt Securities to be issued under the
            indenture (the "Senior Subordinated Debt Indenture") to be entered
            into between the Registrant and the Trustee have been duly
            authorized and, assuming the due authorization of the Senior
            Subordinated Debt Indenture by the Trustee, (i) when the final terms
            thereof have been duly established and approved, the form of Senior
            Subordinated Debt Indenture has been finalized and has been duly
            executed and delivered and the Senior Subordinated Debt Securities
            have been duly executed by the Registrant, in each case pursuant to
            the authority granted by the Board of Directors of the Registrant,
            (ii) upon the execution and delivery by the Registrant and the
            Trustee and, if required by the Senior Subordinated Debt Indenture,
            a supplement to the Senior Subordinated Debt Indenture, and (iii)
            when the Senior Subordinated Debt Securities have been authenticated
            by the Trustee and issued in accordance with the terms of the Senior
            Subordinated Debt Indenture and delivered to and paid for by the
            purchasers thereof, the Senior Subordinated Debt Securities will
            constitute valid and legally binding obligations of the Registrant
            entitled to the benefits of the Senior Subordinated Debt Indenture;

      3.    the Junior Subordinated Debt Securities to be issued under each of
            two indentures (each a "Junior Subordinated Debt Indenture") to be
            entered into between the Registrant and the Trustee have been duly
            authorized and, assuming the due authorization of the applicable
            Junior Subordinated Debt Indenture by the Trustee, (i) when the
            final terms thereof have been duly established and approved, the
            form of Junior Subordinated Debt Indenture has been finalized and
            has been duly executed and delivered and the Junior Subordinated
            Debt Securities have been duly executed by the Registrant, in each
            case pursuant to the authority granted by the Board of Directors of
            the Registrant, (ii) upon the execution and delivery by the
            Registrant and the Trustee and, if required by the applicable Senior
            Subordinated Debt Indenture, supplement to the applicable Junior
            Subordinated Debt Indenture, and (iii) when the Junior Subordinated
            Debt Securities have been authenticated by the Trustee and issued in
            accordance with the terms of the applicable Junior Subordinated Debt
            Indenture and delivered to and paid for by the purchasers thereof,
            the Senior Subordinated Debt Securities will constitute valid and
            legally binding obligations of the Registrant entitled to the
            benefits of the applicable Junior Subordinated Debt Indenture;


      4.    the Preferred Stock has been duly authorized and (i) when the final
            terms thereof have been duly established and approved and the
            applicable Certificate of Designation for the particular series of
            stock to be issued has been duly filed with the Office of the
            Secretary of State of Delaware, in each case pursuant to the
            authority granted by the Board of Directors of the Registrant, and
            (ii) when the Preferred Stock has been duly issued in accordance
            with the terms of the applicable definitive purchase, underwriting
            or similar agreement approved by the Board, and delivered to and
            paid for (in an amount at least



            equal to the par value) by the purchasers thereof, the Preferred
            Stock will constitute a valid and legally binding obligation of the
            Registrant;

      5.    the Depositary Shares have been duly authorized and (i) upon
            execution and delivery by the Registrant and a bank or trust company
            to be selected by the Registrant of a deposit agreement (the
            "Deposit Agreement"), (ii) when the final terms of the particular
            series of Preferred Stock to be issued in connection therewith have
            been duly established and approved and the applicable Certificate of
            Designation has been duly filed with the Office of the Secretary of
            State of Delaware, (iii) when the final terms of the Depositary
            Shares and of their issuance and sale have been duly established in
            conformity with the terms of the Deposit Agreement, (iv) when
            applicable Preferred Stock has been duly issued in accordance with
            the terms of the applicable definitive purchase, underwriting or
            similar agreement approved by the Board, and delivered to and paid
            for by the purchasers thereof, and (v) when receipts evidencing the
            Depositary Shares are duly issued against the deposit of the
            applicable series of Preferred Stock in accordance with the Deposit
            Agreement, the Depositary Shares will constitute a valid and legally
            binding obligation of the Registrant entitled to the benefits of the
            Deposit Agreement;

      6.    the Common Stock has been duly authorized and when the Common Stock
            has been duly issued in accordance with the terms of the applicable
            definitive purchase, underwriting or similar agreement approved by
            the Board, and delivered to and paid for (in an amount at least
            equal to the par value) by the purchasers thereof, the Common Stock
            will constitute a valid and legally binding obligation of the
            Registrant;

      7.    the Warrants have been duly authorized and (i) upon execution and
            delivery by the Registrant and a bank or trust company as the
            warrant agent of a warrant agreement, if applicable, (the "Warrant
            Agreement"), and (ii) when the Warrants have been duly issued and
            delivered to and paid for by the purchasers thereof, the Warrants
            will constitute a valid and legally binding obligation of the
            Registrant entitled to the benefits of the Warrant Agreement;

      8.    the Stock Purchase Contracts have been duly authorized and (i) upon
            execution and delivery by the Registrant and each other party
            thereto of the Stock Purchase Contracts, (ii) when the terms of any
            collateral or other security arrangements relating to such Stock
            Purchase Contracts have been duly established and the agreement(s)
            relating thereto have been duly executed and delivered by each of
            the parties thereto and any collateral has been deposited with the
            collateral agent in accordance with such arrangements, and (iii)
            when the Stock Purchase Contracts have been duly issued and
            delivered to and paid for by the purchasers thereof, the Stock
            Purchase Contracts will constitute a valid and legally binding
            obligation of the Registrant;

      9.    the Units have been duly authorized and (i) upon execution and
            delivery by the Registrant and a bank or trust company of a unit
            agreement (the "Unit Agreement"), and (ii) when the Units have been
            duly issued and delivered to and paid for by the purchasers thereof,
            the Units will constitute a



            valid and legally binding obligation of the Registrant entitled to
            the benefits of the Units Agreement, the Units will constitute a
            valid and legally binding obligation of the Registrant entitled to
            the benefits of the Unit Agreement; and

      10.   the Guarantees have been duly authorized and (i) upon execution and
            delivery by the Registrant and a bank or trust company, as guarantee
            trustee (the "Guarantee Agreement"), (ii) the Trust(s) issuing the
            Securities to which such Guarantees relate have been duly
            authorized, executed and delivered, the Guarantees will constitute a
            valid and legally binding obligation of the Registrant entitled to
            the benefits of the Guarantee Agreement.

      The opinion set forth above is subject to the effects of (a) bankruptcy,
insolvency, fraudulent conveyance, reorganization, moratorium and other similar
laws relating to or affecting the enforcement of creditors' rights generally,
(b) general equitable principles (whether considered in a proceeding in equity
or at law), (c) an implied covenant of good faith and fair dealing, (d)
provisions of law that require that a judgment for money damages rendered by a
court in the United States be expressed only in United States dollars, (e)
limitations by any governmental authority that limit, delay or prohibit the
making of payments outside the United States and (f) generally applicable laws
that (i) provide for the enforcement of oral waivers or modifications where a
material change of position in reliance thereon has occurred or provide that a
course of performance may operate as a waiver, (ii) limit the availability of a
remedy under certain circumstances where another remedy has been elected, (iii)
limit the enforceability of provisions releasing, exculpating or exempting a
party from, or requiring indemnification of a party for, liability for its own
action or inaction, to the extent the action or inaction involves gross
negligence, recklessness, willful misconduct or unlawful conduct, (iv) may,
where less than all of a contract may be unenforceable, limit the enforceability
of the balance of the contract to circumstances in which the unenforceable
portion is not an essential part of the agreed exchange, (v) may limit the
enforceability of provisions providing for compounded interest, imposing
increased interest rates or late payment charges upon delinquency in payment or
default or providing for liquidated damages or for premiums upon acceleration
and (vi) limit the waiver of rights under usury laws. I express no opinion as to
whether, or the extent to which, the laws of any particular jurisdiction apply
to the subject matter hereof, including, without limitation, the enforceability
of the governing law provision contained in any Securities and their governing
documents.

      This opinion is given on the basis of the law and the facts existing as of
the date hereof. I assume no obligation to advise you of changes in matters of
fact or law which may thereafter occur. My opinion is based on statutory laws
and judicial decisions that are in effect on the date hereof, and I do not opine
with respect to any law, regulation, rule or governmental policy which may be
enacted or adopted after the date hereof.

      The foregoing opinions are limited to the federal laws of the United
States, the laws of the State of New York and the laws of the State of Michigan,
and I am expressing no opinion as to the effect of the laws of any other
jurisdiction.

      The Registrant has received opinions regarding the Trust Preferred
Securities from Richards, Layton & Finger, P.A., special Delaware counsel for
the Corporation and the Issuer Trust. I am expressing no opinion with respect to
the matters contained in such opinions.



         This opinion is intended solely for use in connection with the
Corporation's Registration Statement on Form S-3 and may not be reproduced,
filed publicly, or relied upon by you for any other purpose or by any other
person for any purpose without our prior written consent.

      I hereby consent to the use of this opinion as an exhibit to the
Registration Statement and to the use of my name under the heading "Legal
Matters" in the Prospectuses without admitting that I am an "expert" within the
meaning of the Act, or other rules and regulations of the Commission issued
thereunder with respect to any part of the Registration Statement, including
this exhibit.

                                    Very truly yours,

                                    /s/ Thomas W. Gallagher
                                    --------------------------
                                    Thomas W. Gallagher
                                    General Counsel and Secretary