A small tax and wealth management law firm is defending itself in a breach-of-fiduciary-duty lawsuit that resulted from its relationship with two oil magnates who are in litigation over the alleged fraudulent transfer of securities.

The parties accused of the fraudulent transfers, Philippe E. Mulacek and his company, Asian Gas Partners Ltd., were sued in federal court. The Mulacek defendants reacted in part by suing attorney James P. Dossey and the Dossey & Jones firm.