The U.S. Justice Department last week heralded blockbuster deals with British banks that netted more than $2 billion in criminal fines and penalties for violations that included transactions with countries subject to U.S. sanctions. But questions persist over whether prosecutors are being aggressive enough in combating corporate misconduct.

Lanny Breuer, the head of DOJ’s Crimi­nal Division, said HSBC Holdings PLC, one of Europe’s largest banks, is being held responsible for “stunning failures of oversight” that allowed Mexican drug traffickers and others to launder hundreds of millions of dollars through the bank’s subsidiaries.