<PAGE>
                                                                     EXHIBIT 4.1

                            PROASSURANCE CORPORATION

                              STOCK OWNERSHIP PLAN

                                DECEMBER 1, 2002

<PAGE>
                                                                               .
                                                                               .
                                                                               .

                                TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                                   Page
                                                                                   ----
<S>                                                                                <C>
1.       Definitions............................................................     1

2.       Administration.........................................................     4

3.       Eligibility............................................................     4

4.       Method of Participation................................................     5

5.       Accounts...............................................................     6

6.       Grants from Corporation................................................     7

7.       Vesting of Grant Shares................................................     7

8.       Distribution and Withdrawal of Shares..................................     8

9.       Forfeiture of Shares...................................................     8

10.      Beneficial Ownership of the Accounts...................................     9

11.      Rights not Transferable................................................     9

12.      Termination or Amendment of Plan.......................................     9

13.      Compliance with Rule 10b5-1............................................     9
</TABLE>

<PAGE>

                              AMENDED AND RESTATED
                            PROASSURANCE CORPORATION
                              STOCK OWNERSHIP PLAN

         Effective December 1, 1992, the Board of Directors of Mutual Assurance,
Inc. adopted the Mutual Assurance, Inc. Open Market Stock Purchase Plan (the
"Plan") to provide incentives to a broad base of employees of Mutual Assurance,
Inc. and its subsidiaries in connection with the purchase of the common stock of
Mutual Assurance, Inc. Following a corporate reorganization, MAIC Holdings, Inc.
assumed the sponsorship of the Plan. Effective August 31, 1995, the name of the
Plan was changed to the MAIC Holdings, Inc. Open Market Stock Purchase Plan,
and, effective on and after August 31, 1995, shares of the common stock of MAIC
Holdings, Inc. were purchased pursuant to the provisions of the Plan. Effective
June 21, 1996, the name of the Plan was changed to the MAIC Holdings, Inc.
Thrift Plan. Thereafter, the corporate name of MAIC Holdings, Inc. was changed
to Medical Assurance, Inc. Effective June 27, 2001, as a result of a corporate
reorganization, shares of the common stock of ProAssurance Corporation (the
"Corporation") were substituted for shares of Medical Assurance, Inc. under the
Plan. Effective January 1, 2002, the Corporation assumed the sponsorship of the
Plan, restated and amended the Plan to make certain changes and improvements
therein, and changed the name of the Plan to the ProAssurance Corporation Stock
Ownership Plan. Effective December 1, 2002, the Plan is being amended and
restated to change the method of matching employee contributions to the Plan.

         1.       DEFINITIONS. For purposes of this Plan, the following terms
shall have the meanings hereinafter described:

                  (a)      The term "Account" shall mean the brokerage accounts
         established with the Agent for each Participant and the Corporation in
         accordance with paragraph 5 below.

                  (b)      The term "Agent" shall mean the independent agent
         appointed by the Plan Administrator to assist it in the administration
         of the Plan as herein provided. Any

<PAGE>

         reference to the Plan Administrator shall be deemed to include the
         Agent to the extent that the Plan Administrator has engaged the Agent
         to perform its obligations hereunder.

                  (c)      The term "Cash Deposit" shall mean the amount
         deducted from the pay of a Participant at his or her election or a lump
         sum payment made by a Participant for the purpose of purchasing shares
         of Common Stock under the Plan.

                  (d)      The term "Change of Control" shall occur, with
         respect to the Corporation or a Participating Employer, when any
         "Person," as defined in Section 3(a)(9) of the Securities Exchange Act
         of 1934 (the "1934 Act"), other than a person in control of the
         Corporation or a Participating Employer on the Effective Date, either
         (i) becomes the "Beneficial Owner," as defined by Rule 13d-3 of the
         regulations promulgated by the SEC under the 1934 Act, directly or
         indirectly, of more than 50.1% of the then outstanding voting
         securities of the Corporation or of a Participating Employer; or (ii)
         purchases or acquires substantially all of the assets of the
         Corporation or a Participating Employer with the result that the
         Corporation or the Participating Employer ceases to function as part of
         an insurance holding company system that offers medical professional
         liability insurance; or (iii) is a party to a merger, consolidation or
         reorganization with the Corporation or a Participating Employer that
         results in the shareholders as of the Effective Date of the Corporation
         or a Participating Employer being the Beneficial Owners of less than
         50.1% of the combined voting power of the surviving entity.

                  (e)      The term "Common Stock" shall mean the common stock
         of the Corporation, having a par value of $.01 each.

                  (f)      The term "Corporation" or "ProAssurance" shall mean
         ProAssurance Corporation, a corporation organized and existing under
         the laws of the State of Delaware.

                  (g)      The term "Director" shall mean an individual who is
         not an Employee and who is serving on the Board of Directors of the
         Corporation or a Participating Employer.

                  (h)      The term "Effective Date" shall mean the effective
         date of this amended and restated plan which is December 1, 2002.

                  (i)      The term "Employee" shall mean each common-law
         employee of a Participating Employer who is scheduled to work at least
         twenty (20) hours per week. An individual who is absent from work due
         to a leave of absence which has been approved by his Participating
         Employer and who, prior to the commencement of such leave of absence,
         was regularly scheduled to work at least twenty (20) hours per week,
         will be considered to be an Employee during such leave of absence,
         provided that such individual returns to active employment immediately
         following the expiration of the leave of absence.

                  (j)      The term "Executive Officer" shall mean an officer of
         the Corporation under the definition of "officer" in Rule 16a-1(f) of
         the regulations promulgated by the SEC under the 1934 Act.

                                       2

<PAGE>

                  (k)      The term "Grant" shall mean a grant made by the
         Corporation to a Participant in accordance with the terms of the Plan.

                  (l)      The term "Grant Proceeds" shall mean the proceeds of
         any Grant made by the Corporation to a Participant.

                  (m)      The term "Grant Shares" shall mean the shares of
         Common Stock purchased for the Account of a Participant with the Grant
         Proceeds attributable to a Grant made to such Participant. Prior to the
         December 1, 2002, Grant Shares were called Loan Shares or "Thirty-Five
         Percent Shares."

                  (n)      The term "Participant" shall mean an Employee who is
         eligible to participate in the Plan and for whom an Account has been
         established.

                  (o)      The term "Participant Shares" shall mean collectively
         the shares of Common Stock deposited by a Participant as Share Deposits
         and the shares of Common Stock purchased for the Account of a
         Participant with his Cash Deposits. Prior to January 1, 2002,
         Participant Shares were called "Sixty-Five Percent Shares."

                  (p)      The term "Participating Employer" shall mean the
         Corporation and each wholly-owned (direct or indirect) subsidiary of
         the Corporation which may elect to participate in the Plan for the
         benefit of its eligible Employees.

                  (q)      The term "Participation Date" shall mean each March
         1st, June 1st, September 1st, and December 1st occurring on or after
         the Effective Date and during the continuance of the Plan; provided,
         however, that if such date is not a business day, the Participation
         Date will be the next business day following such March 1st, June 1st,
         September 1st, or December 1st.

                  (r)      The term "Participation Period" shall mean each three
         (3) month period commencing on a Participation Date.

                  (s)      The term "Plan" shall mean this Amended and Restated
         ProAssurance Corporation Stock Ownership Plan, as the same may from
         time to time be amended.

                  (t)      The term "Plan Administrator" shall mean the
         Corporation, unless the Corporation shall elect to appoint another
         entity or person as the Plan Administrator.

                  (u)      The term "Plan Year" shall mean the calendar year.

                  (v)      The term "Retirement" shall mean a Participant's
         termination of employment at or following his attainment of the age of
         fifty-five (55) or prior thereto with the consent and approval of his
         Participating Employer.

                  (w)      The term "Share Deposit" shall mean the shares of
         Common Stock deposited by a Participant with the Plan Administrator in
         accordance with the terms of the Plan.

                                       3

<PAGE>

                  (x)      The term "Value" shall mean, with respect to the
         valuation of each share included in a Share Deposit on the March 1st
         Participation Date, the average closing price of a share of Common
         Stock as reported by the New York Stock Exchange on each business day
         during the calendar month of December.

         2.       ADMINISTRATION. The Plan Administrator will be responsible for
the administration of the Plan including, without limitation, the determination
of the eligibility of Employees to participate in the Plan, the collection of
Cash Deposits and Share Deposits from Participants, the making of Grants, the
purchase of Shares of Common Stock, and the allocation of such shares of Common
Stock to the Accounts of Participants, and the maintenance of Account records.
The Plan Administrator shall also have the right to interpret the Plan and its
determinations shall be conclusive and binding on all parties. To assist it in
the administration of the Plan, the Corporation may appoint one or more Agents
to perform any or all of the functions of the Plan Administrator. The expenses
of the Agent(s) under the Plan shall be paid by the Company.

         3.       ELIGIBILITY. An Employee or Director will become eligible to
participate in the Plan in accordance with the following:

                  (a)      Any Employee who has completed at least six (6)
         months of employment with one or more Participating Employers and any
         Director who has served as a member of the Board of Directors of
         ProAssurance or one or more Participating Employers for at least six
         (6) months during the calendar year ending December 31, 2002, is
         eligible to participate in the Plan on the Effective Date.

                  (b)      After the Effective Date, any Employee who completes
         at least six (6) months of employment with one or more Participating
         Employers and any Director who serves on the Board of Directors of
         ProAssurance or one or more Participating Employers for at least six
         (6) months will be eligible to participate in the Plan commencing with
         the first day of any Participation Period thereafter, provided that he
         is in the active service of the Participating Employer or on an
         approved leave of absence on such date.

                  (c)      No Employee or Director can participate in the Plan
         if such Employee or Director, at any time immediately after the stock
         is purchased under the Plan, owns stock possessing five percent (5%) or
         more of the total combined voting power or value of all classes of
         stock of the Corporation. For purposes of determining the stock
         ownership percentage of an Employee and Director: (i) the Employee or
         the Director shall be considered as owning the stock owned, directly or
         indirectly, by or for his brothers and sisters (whether by the whole or
         half blood), spouse, ancestors, and lineal descendants; and (ii) stock
         owned, directly or indirectly, by or for a corporation, partnership,
         estate, or trust, shall be considered as being owned proportionately by
         or for its shareholders, partners, and beneficiaries.

                  (d)      If a Participant elects to stop making Cash Deposits
         during a Participation Period, such Participant must wait until the
         next Plan Year to reenroll in the Plan.

                                       4

<PAGE>

                  (e)      Prior to participation in the Plan, each Employee
         must establish one or more Accounts in the form of investment brokerage
         accounts with the Agent as directed by the Plan Administrator. The
         Company will bear the cost of all Accounts required to be maintained
         with the Agent under the Plan.

         4.       METHOD OF PARTICIPATION.

                  (a)      An Employee or Director who is eligible to
         participate in the Plan may become a Participant during any
         Participation Period by executing and filing with the Plan
         Administrator a written enrollment form (in such form as may be
         prescribed by the Plan Administrator from time to time) for any one of
         the following elections:

                           (i)      A Participant who is not an Executive
                  Officer or Director of the Corporation may elect to make Cash
                  Deposits or Share Deposits during a Participation Period by
                  either of the following methods:

                                    (A)      Cash Deposits through payroll
                           deductions may be made during a Participation Period
                           by completing, executing and filing an enrollment
                           form with the Plan Administrator at least thirty (30)
                           days prior to the commencement of such Participation
                           Period indicating thereon the total dollar amount
                           that such Participant desires to be deducted from his
                           compensation during such Participation Period. The
                           Cash Deposits through payroll deductions are subject
                           to a minimum rate of $5.00 for each regularly
                           scheduled compensation payment during the
                           Participation Period. A Participant may elect to
                           terminate his election to make Cash Deposits through
                           payroll deductions at any time by delivery of written
                           notice to the Plan Administrator in which event no
                           further installments of the Cash Deposit will be paid
                           from his compensation during such Participation
                           Period; or

                                    (B)      Lump sum Cash Deposits or Share
                           Deposits may be made only during the month of January
                           in each Plan Year, by completing, executing and
                           filing an enrollment form with the Plan Administrator
                           and making the lump sum Cash Deposit or Share Deposit
                           prior to the March 1st Participation Date in the
                           applicable Plan Year; provided that the minimum
                           amount of any lump sum Cash Deposit, and the minimum
                           Value of any lump sum Share Deposit, shall be $1000.

                           (ii)     In order to facilitate SEC reporting of
                  share purchases (if necessary), a Participant who is an
                  Executive Officer or Director of the Corporation may elect
                  only to make lump sum Cash Deposits or Share Deposits. No
                  payroll deductions shall be made under the Plan for any
                  Executive Officer or Director.

                           (iii)    The Corporation shall fund Grants with
                  respect to the Cash Deposits and Share Deposits made during a
                  Participation Period within thirty (30) days after the
                  expiration of such Participation Period.

                                       5

<PAGE>

                  (b)      On or before the later of (1) the fifth (5th)
         business day following the funding of the Grant, or (2) the earliest
         date on which shares of Common Stock are reasonably available for
         purchase, the Plan Administrator will apply the cash held in the
         Accounts at the end of the prior Participation Period toward the
         purchase of such number of shares of Common Stock as can then be
         purchased in ordinary brokerage transactions in the public market. The
         Plan Administrator will allocate the shares so purchased (including
         fractional shares) to the Accounts as provided in paragraph 5 below and
         shall notify the Participant of the shares allocated to his or her
         Participant Shares Subaccount and Grant Shares Account.

                  (c)      The Plan Administrator shall make reasonable effort
         to ensure that the Participants who are Executive Officers and
         Directors of ProAssurance receive the notice within three (3) business
         days of the purchase of the shares allocated to the Accounts of the
         Participant.

         5.       ACCOUNTS. The Plan Administrator shall establish and maintain
the following Accounts under the Plan. The Agent and the Plan Administrator are
authorized to use and share information with each other regarding the Accounts
in connection with the administration of the Plan.

                  (a)      Participant Accounts. The Plan Administrator shall
         hold all Share Deposits, Cash Deposits and shares of Common Stock
         purchased with the Cash Deposits in the Participant Accounts until
         distributed in accordance with the Plan and shall cause the following
         subaccounts to be established and maintained in the name of each
         Participant.

                           (i)      Cash Subaccounts. All Cash Deposits made to
                  a Participant Account and the earnings thereon shall be
                  credited to the Cash Subaccount maintained for such
                  Participant until applied to the purchase of Common Stock
                  hereunder. Pending such purchase, the funds may be invested in
                  short term obligations such as money market funds, savings
                  accounts and/or certificates of deposit, in which event
                  interest and other investment gains attributable to the
                  Participant will be credited to the Cash Subaccount.

                           (ii)     Participant Shares Subaccounts. All Share
                  Deposits made by a Participant and all shares of Common Stock
                  purchased with funds from the Cash Subaccount of such
                  Participant shall be credited to the Participant Shares
                  Subaccount maintained for such Participant.

                  (b)      Corporation Accounts. The Plan Administrator shall
         hold all Grant Proceeds and Grant Shares in the Corporation Accounts
         until sold or distributed in accordance with the Plan and shall
         maintain the following subaccounts:

                           (i)      Grant Shares Accounts. Until fully vested,
                  Grant Shares may be held in one or more commingled Grant Share
                  Accounts as designated by the Plan Administrator. The Plan
                  Administrator shall maintain records reflecting the number of
                  unvested Shares held for each Participant. All Grant Shares
                  allocated

                                       6

<PAGE>

                  to a Participant in accordance with the Plan shall be credited
                  to a Grant Shares Subaccount maintained for each Participant.

                           (ii)     Forfeiture Account. Any Grant Shares that
                  are forfeited under the Plan shall be credited to the
                  Forfeiture Account as herein provided.

         6.       GRANTS FROM CORPORATION. The Corporation shall make a matching
Grant to each Participant who participated in the Plan during the preceding
Participation Period on the terms and conditions hereinafter set forth:

                  (a)      The amount of the Grant will be based on the amount
         of the Cash Deposits and Share Deposits made by the Participant during
         the Plan Year as follows:

                           (i)      The Company will make a Grant to the
                  Participant equal to 100% of the first $2,000 of the sum of
                  the Cash Deposits and the Value of Share Deposits made during
                  any Plan Year; and

                           (ii)     The Company will make a Grant to the
                  Participant equal to 50% of the next $8,000 of the sum of the
                  Cash Deposits and the Value of Share Deposits made during the
                  Plan Year.

                  (b)      The Grant shall be funded by the Corporation in
         accordance with subparagraph 4 (a) (iii) above.

                  (c)      The Grant proceeds will be applied to the purchase of
         shares of Common Stock in accordance with subparagraph 4 (b) above.

         7.       VESTING OF GRANT SHARES.

                  (a)      The Grant Shares allocated to a Participant shall
         become fully vested and shall not be subject to forfeiture upon the
         occurrence of the sooner of the following:

                           (i)      The Participant has been an Employee of a
                  Participating Employer continuously for a period of three
                  years from the Participation Date for the Participation Period
                  in which the Grant Shares are purchased; or

                           (ii)     The Participant ceases to be an Employee of
                  a Participating Employer by reason of (A) a determination by
                  the Corporation that the Participant is disabled by illness or
                  injury from performing his duties as an Employee; (B) the
                  death of the Participant; or (C) the Retirement of the
                  Participant; or

                           (iii)    The Change of Control of a Participant's
                  employer (other than the Corporation); unless the Participant
                  becomes an Employee of another Participating Employer within
                  thirty (30) days after such Change of Control; or

                           (iv)     The Change of Control of the Corporation.

                                       7

<PAGE>

                  (b)      The Grant Shares shall be transferred to the
         Participant Share Account of the Participant upon vesting, subject to
         the payment of federal and state withholding requirements. The Plan
         Administrator shall have the right to withhold such number of the Grant
         Shares as may be necessary to generate funds to pay federal and state
         withholding taxes. The Agent may cause the withheld shares to be sold
         in the public market for the account of the Participant and the
         proceeds of the sale shall be distributed to the Corporation to fund
         the payment of such withholding taxes.

         8.       DISTRIBUTION AND WITHDRAWAL OF SHARES.

                  (a)      Promptly after vesting of the Grant Shares, the Plan
         Administrator shall distribute to the Participant, or to an investment
         brokerage account owned by the Participant, from the Participant Shares
         Account (i) the vested Grant Shares and (ii) the Participant Shares
         purchased with Cash Deposits or delivered as a Share Deposit upon which
         the Company made the Grant used to purchase the vested Grant Shares.
         Until distributed as stated in this subparagraph (a), the shares of
         Common Stock held in the Participant Shares Account shall be subject to
         withdrawal in accordance with the provisions of subparagraph (b) below.

                  (b)      A Participant may withdraw the shares of Common Stock
         held in the Participant Shares Subaccount maintained for such
         Participant at any time. In the event that a Participant withdraws
         shares from his or her Participant Shares Account, the shares subject
         to withdrawal shall be taken from the shares that have been credited to
         the Participant Shares Account for the longest period of time in the
         inverse order that such shares were credited to the Participant Shares
         Subaccount. The withdrawal of any shares of Common Stock from a
         Participant's Participant Shares Subaccount shall be subject to the
         provisions of Section 9(b) hereof.

                  (c)      Grant Shares shall be distributed from the Grant
         Shares Account only upon vesting in accordance with paragraph 7 hereof
         or upon forfeiture in accordance with paragraph 9 hereof.

         9.       FORFEITURE OF SHARES.

                  (a)      In the event that a Participant ceases to be an
         Employee of a Participating Employer (for reasons other than those
         described in Section 7(a)(ii) above), all unvested Grant Shares
         credited to the Participant in a Grant Shares Account shall be
         forfeited and transferred to the Forfeiture Account.

                  (b)      In the event that a Participant withdraws shares of
         Common Stock from his or her Participant Shares Subaccount that were
         credited to said account, any unvested Grant Shares purchased with
         Grant Proceeds made with respect to the shares so withdrawn, determined
         in accordance with Section 8(f) hereof, shall be forfeited and
         transferred from the Participant's Grant Shares Account to the
         Forfeiture Account.

                                       8

<PAGE>

         10.      BENEFICIAL OWNERSHIP OF THE ACCOUNTS.

                  (a)      The Participant will be the beneficial owner of the
         Participant Shares held by the Plan Administrator for the Account of a
         Participant. The Participant will have the right to vote such shares at
         any meeting of the shareholders of the Corporation and will receive all
         communications addressed by the Corporation to its shareholders. All
         dividends (other than stock dividends) paid with respect to such shares
         shall, at the option of the Corporation, either be paid to the
         Participant or credited to the Cash Subaccount of a Participant. Stock
         dividends or stock splits paid with respect to Participant Shares shall
         be credited to the Participant Shares Subaccount. If the Corporation
         shall offer any subscription rights to its shareholders, the Plan
         Administrator shall to the extent it is able provide to each
         Participant who then has shares of Common Stock allocated to his
         Participant Shares Subaccount the right to exercise, sell, or assign,
         in accordance with the terms thereof, all subscription rights issued
         with respect to the shares in his Account and to receive any shares
         subscribed for, free from pledge.

                  (b)      The Corporation shall be the owner of the Grant
         Shares as treasury shares until they become vested. The Corporation may
         not vote, sell or withdraw any shares of Common Stock held in the Grant
         Shares Account. The Corporation shall have the right to withdraw shares
         of Common Stock held in the Forfeiture Account at any time free and
         clear of any claims of Participants under the Plan.

         11.      RIGHTS NOT TRANSFERABLE. No Participant shall be permitted to
sell, assign, transfer, pledge, or otherwise dispose of or encumber either his
right to participate in the Plan or his interest in any shares of Common Stock
being held by the Plan Administrator for the Account of a Participant prior to
the withdrawal or distribution thereof as herein contemplated. Except as
otherwise provided by law, the right and interest of a Participant under the
Plan shall not be liable for or subject to the debts, contracts or liabilities
of such Participant.

         12.      TERMINATION OR AMENDMENT OF PLAN. The Corporation reserves the
right to amend, modify, suspend, or terminate the Plan at any time without
notice, provided that no such amendment, modification, suspension, or
termination shall adversely affect, without the Participant's written consent,
any shares of Common Stock previously issued to the Participant.

         13.      COMPLIANCE WITH RULE 10b5-1. It is the intention of the
Corporation that provisions of the Plan be interpreted and administered so that
purchases and sales of Common Stock under the Plan will be transactions pursuant
to a contract, instruction or written plan that satisfies the affirmative
defense conditions of Rule 10b5-1(c) promulgated by the SEC under the 1934 Act.

         14.      PRIOR PARTICIPANT SHARES AND LOAN SHARES. The rights and
obligations of Participants and the Corporation under the Plan prior to December
1, 2002, shall not be modified as a result of this amendment and restatement of
the Plan. The rights and obligations of Participants with respect to Participant
Shares and Loan Shares purchased and pledged prior to December 1, 2002, shall be
governed by the terms of the Plan in effect as of the date of the purchase or
deposit of the Participant Shares and the funding of the Loans, except to the
extent the Plan has been amended to reflect the assumption of the Plan by the
Corporation.

                                       9