Sitting on the witness stand last week in District of Columbia Superior Court, Elliott Portnoy, the chairman of SNR Denton U.S., got tangled up with a plaintiffs’ lawyer.

Portnoy, who previously chaired Son­nenschein Nath & Rosenthal, was testifying in a suit a former partner filed in 2005 over allegations the firm owes him more than $1 million in legal fees.