Large law firms are earning millions of dollars in their white-collar defense and government investigation practices—but it's not only because of federal agencies pursuing more enforcement actions.

Increasingly, law firms are seeing demand from proactive clients before litigation or enforcement begins.

For instance, Michael Murray, co-chair of the antitrust and competition practice at Paul Hastings, said in light of recent guidelines from the FTC and Justice Department, more clients are wanting to be proactive in engaging with the agencies.