Amended Rule 1.09(b), which has been totally rewritten, addresses situations when lawyers move between firms. It operates to disqualify a lawyer who has moved firms when the lawyer has actual knowledge of confidential client information. A simplified example of this is as follows:  

Firm A represented Wife in divorce from Husband;  Lawyer X did not work on Wife’s case at Firm A, and obtained no confidential information about Wife;  Lawyer X leaves Firm A to go to Firm B;  Firm B is subsequently contacted to represent Husband in a modification proceeding related to the divorce. 

On these facts, Lawyer X’s migration to Firm B does not conflict Firm B from representing Husband.  See, Cmt. 4 to Rule 1.09. However, if challenged, Firm B will have the burden of proof to show that  Lawyer X while at Firm A was only privy to information about clients he actually served, and not those of…