Step into any of 2,600-lawyer Hogan Lovells' 51 offices worldwide, and prepare to bump into more than a few partners who know their way around a criminal indictment.

The firm employs 141 lawyers worldwide who are engaged in white-collar criminal defence and investigations practices, including 42 partners and five who hold firm leadership positions, including Steve Immelt, CEO since 2014, and a former assistant US attorney in Maryland.

Not surprisingly, Immelt is eager to extoll the virtues of a strong white-collar criminal defence and investigations practice at big law firms like his.

"The upside is terrific. They are large matters that involve lots of people," he said. His firm's rivals - he cited Skadden Arps Slate Meagher & Flom; Gibson Dunn & Crutcher, Wilmer Cutler Pickering Hale and Dorr  and Covington & Burling - "have all done extremely well" with such practices, Immelt added.

His list, however, could extend much further.

According to research by ALM Legal Intelligence, the number of partners who identify white-collar criminal defence and investigations practices as their primary focus has more than doubled at top 200 US law firms since 2011. That was the year Charles Weisselberg, a law professor at the University of California at Berkeley School of Law, published "Big Law's Sixth Amendment: The Rise of Corporate White-Collar Practices in Large US Law Firms."

Using Am Law 200 data available at the time, Weisselberg identified 1,626 partners with substantial white-collar and internal investigations practices. This month, ALM Legal Intelligence combed the 2017 Am Law rankings and found 3,472 partners who were identified as having substantial white-collar criminal defence and internal investigations practices.

For his study, Weisselberg also identified the number of partners with white-collar criminal defense and investigations practices who had moved into firm leadership positions - at least 240 fit that description back then, the law professor calculated.

Mark Filip, a Kirkland & Ellis partner in Chicago and Washington DC, who previously served as second-in-command at the US Department of Justice, wears multiple leadership hats at his 2,000-plus lawyer firm, which has 60 partners and 30 other lawyers engaged in its white-collar criminal defence and investigations practices. Filip leads Kirkland's government enforcement defence and internal investigations group, co-leads its litigation department, and sits on its 15-member worldwide management committee.

"Government investigations and litigation against corporations has increased substantially in recent years - because of the growth of qui tam suits, state attorney general-led suits, and the overall expansion of federal regulation. As a result, white-collar and regulatory practices have expanded in a similar way," Filip said in an email. "Many of the lawyers who practice in this area have strong experience, both in court and as leaders, in high-stakes situations when they served in the government, and many of them have continued to apply those skills and experiences in private practice within their firms."

At 2,500-plus-lawyer Jones Day, about 75 lawyers are part of the firm's white-collar criminal defence and investigations practices. Jones Day boasts more than 40 former federal prosecutors, including four former US attorneys.

Ted Chung, a partner and leader of the firm's investigations and white-collar defence practice group, tags corporate clients' demand as the reason for the growth. "Clients need these services. There is a higher level in sophistication in board rooms and corporate leadership about the value of conducting an internal investigation, even if there isn't an ongoing government investigation," he said. "A lot of it is about understanding the facts," he added.

With the growth of international regulatory scrutiny, particularly surrounding bribery allegations, Chung forecasts Big Law's love affair with white-collar criminal defence practices and prosecutorial experience won't end any time soon.

Hogan Lovells' Immelt agreed. "Firms are making this investment … because of the number and variety of people doing those investigations," he said. "At one time, it was just the US attorneys and DOJ - now you've got global players and state attorney generals. It's a natural response to the needs of the clients for sophisticated legal advice in matters that could hurt them both reputationally and financially."