This article, written by two legal search placement consultants, recomends some strategies for exiting your current firm.  As always, be mindful that a general article such as this must be read in light of any specific case law or ethics decisons on this matter in your state (in Missouri, Cupples, for example).  Nevertheless, it does raise important issues lawyers should consider before making their exit announcement.    

Because Missouri Rule 4-1.5, governing division of fees between lawyers in different firms, does not apply to fees accruing to lawyers in one firm before separation into different firms a lawyer’s claim against former partners for accounting and conversion of fees earned while firm was still intact need not allege compliance with rule. 

The best way to avoid acrimonious and expensive litigation over fees when a lawyer leaves a firm is for the lawyers to have a carefully thought out policy addresing the the issue BEFORE it arises.   While it may be fairly easy to determine the application of Rule 4-1.5 on hourly fees, it may be more difficult to fashion a policy that complies with the rule in siutations where a contingent fee is involved.  Review of informal opinions addressing that matter are a starting point.  Ultimately, inquiries to the Missouri Legal Ethics Counsels Office are recommended to ensure that the policy can withstand scrutiny under the Missouri Rules of Professional Conduct.   

The first step for Missouri lawyers when planning to leave their firm is to read In re Cupples, 979 S.W.2nd 932 (Mo. 1998).

From the opinion: "Prior to withdrawal, lawyers within a firm have a duty to treat each other fairly and honestly and to put the interests of the law firm regarding firm business before their individual interests. The lawyer may not compete with the firm for business opportunities. Each lawyer has a duty to the firm to represent firm clients diligently, competently, and zealously.

After an attorney withdraws from a firm, the fiduciary duties no longer prohibit competition. However, the firm and the departing attorney have a duty to deal in good faith in winding up the firm business. Both the withdrawing attorney and the firm have a duty to inform firm clients of any material change in representation and to obtain the clients' informed direction as to how the client wishes its work to be handled. The withdrawing attorney and the firm also have a duty to orderly maintain or transfer the clients' files in accordance with the clients' directions and to withdraw from representing those clients by whom they are discharged. Both the withdrawing attorney and the firm have a mutual duty, not only to the client, but to each other as well, to make certain that these tasks are completed in a competent and professional manner to the reasonable satisfaction of their clients."