After an illustrious twenty-year career as a senior assistant district attorney in Kent County, State of Tudor, Perry Mason is ready to give it up. He prosecuted some of the highest-profile cases in Kent over the years, and put dozens of criminals behind bars. Now he's had enough of criminal prosecution, and thinks that his life would be less stressful if he moved over into corporate law. Because of his famous name and career, he is offered and accepts a position as senior litigator at Dewey, Cheatem & Howe, LLP.

One of his first assignments is to represent the Kent County Employees' Union Local 451 in its efforts to merge with the New Tudor Employees United Workers Local 37. He soon realizes, after delving into the client's files, that the president of Local 451 is none other than Jimmy Tuffit, who spent 10 years in state prison after Perry successfully prosecuted him for taking bribes in connection with a different union.

Please discuss what the ethical issue is and what Model Rule governs this situation. Be sure to include in your discussion:

1. Whether Perry Mason is even permitted to work at Dewey, Cheatem & Howe;
2. If so, whether Perry may continue to represent Local 451 in this matter; and
3. What steps DC&H must take if Perry is to continue working for the firm.