Regardless of their political leanings, many law firm leaders were cautiously optimistic after Donald Trump's election. They hoped he might boost business—and demand for legal services—with his agenda of tax reform, looser bank regulations and infrastructure investment.

But with the fledgling administration already mired in investigations and litigation over topics ranging from Russia to immigration reform, the enthusiasm is waning amid some firm leaders.

“There remains hope, but I think the hope is tempered by reality, whereas I think there was a lot more optimism in late November, December and January,” said Richard Cogen, a Nixon Peabody partner and co-leader of its energy and infrastructure projects team.