As the reality of Donald Trump's unexpected victory begins to sink in, law firm leaders have begun to assess how the momentous election may affect their own firms' bottom lines.

Nearly all of those spoken to for this article said that Trump's presidency will initially mean more work for many lawyers, with practice areas such as healthcare, tax and international trade almost certainly poised for increased activity. Long-term repercussions are harder to predict, but few expect the status quo.

Trump's campaign messages did not hew to conventional political lines on economic issues. While he embraced many policies favoured by conservatives, such as lower taxes, he also talked about reinstating the Glass-Steagall Act, a position often favoured by liberal critics of big banks.

Healthcare

Trump has been clearer about his intentions in some areas than others. He has vowed to eliminate the Affordable Care Act, or Obamacare, which would unleash a host of changes in healthcare law. Ira Coleman, who heads the health practice at McDermott Will & Emery and will take over as firm chairman at the start of next year, says he's preparing for things to be busy.

"We have a $3trn healthcare industry that is heavily regulated," he says. "For big law firms, changes to the regulatory and legal environment are always good for business."

Elizabeth Halpern, a partner in the health law practice of Hogan Lovells, says she spent all Wednesday morning answering questions from clients. Lawyers in her field are used to change, she says. "Every five to seven years we have some big legislative change," she adds.

Even if Obamacare is repealed or cut back, Halpern says she still expects significant activity. "There are concerns about fraud and abuse and I don't really see much interest in getting rid of the regulation of that," she says. "Regulation doesn't dry up because there's a Republican administration. It just might change form."

Finance and M&A

M&A may be one area that is disrupted in the short term. Ed Batts, co-head of Orrick Herrington & Sutcliffe's global M&A practice, says he'd expect many companies to take a brief pause when it comes to potential transactions.

If Trump follows through on a plan to offer a lower corporate tax rate for companies that repatriate some of their offshore cash into the US, it could put a damper on the types of inversion deals that have kept many tax and transactional lawyers busy in recent years. But it could also open up new types of deals. "From my practice group level… this is going to be an interesting change," Batts says.

No one really knows what Trump really believes. It's very difficult to separate his campaign rhetoric from real policy

Douglas Doetsch, the head of Mayer Brown's Latin America/Caribbean practice and co-head of its global banking and finance practice, also fielded calls from clients Wednesday morning. "It's a surprise in Latin America, and an unwelcome surprise," says Doetsch about Trump's election. Mayer Brown has an affiliate with about 180 lawyers in Brazil and an eight-person office in Mexico City that focuses on infrastructure and energy.

Competition

When it comes to specific antitrust policies, Trump has said little. "Anyone who tells you they know what's coming in antitrust enforcement in a Trump administration is making it up," says David Wales, the head of the antitrust practice at Jones Day. He points out that Trump has voiced his opposition to the proposed Time Warner/AT&T merger, saying it concentrates too much power.

Wales says it's highly unlikely that the Time Warner deal would be cleared before Trump takes office, leaving the merger's fate with Trump. "Trump will have to decide if he will continue that populist view of antitrust enforcement or go back to solid economics."

Recent months have seen many firms taking steps to bulk up their antitrust practices, as the Federal Trade Commission (FTC) and Department of Justice have challenged deals. Boies Schiller & Flexner antitrust partner Richard Feinstein, a former director of the FTC's Bureau of Competition, says he doesn't expect a Trump presidency will spell a major change of course.

"He certainly showed signs during the campaign of wanting to be pretty aggressive in antitrust enforcement," Feinstein says. "I don't think there's any reason to assume that antitrust activity will necessarily decline."

Trade

Opposition to Chinese imports and the North American Free Trade Agreement (NAFTA) were both hallmarks of Trump's candidacy. Manufacturers in North America are particularly unsettled about the fate of NAFTA, which Trump attacked during his campaign, and the possibility of tariffs for Mexican imports, says Mayer Brown's Doetsch. He says he doesn't believe Trump will kill the agreement, and adds that he is more likely to renegotiate it.

"But no one really knows what Trump really believes," Doetsch says. "It's very difficult to separate his campaign rhetoric from real policy. I think there is tremendous uncertainty."

Clients in Europe and Germany were already dealing with uncertainty over Brexit. Dieter Schmitz, an M&A partner at Baker & McKenzie who specialises in cross-border deals involving Europe and Germany, says he's had to reassure European clients confused by Trump's presidency. His response: "Don't be surprised by surprises."

"I lived in Germany when Ronald Reagan was the president and everyone said, 'How can an actor be president of United States?'" he says. "I lived in Europe when Jimmy Carter was president, and they asked, 'How can a peanut farmer be president?' And folks ask, 'How can Donald Trump become president?' And every time I say: 'That's what democracy allows people to do.'"

Markets and businesspeople would adjust to a Trump presidency in the same way they're adjusting to Brexit, he says. "You have to assume every single day that there will be something that rocks you," he adds.

The rule of law

Some leaders of big law firms are also calling on the profession to take a more vocal and visible stand to protect the rule of law. "Given the election and its many implications, there has been no moment in recent memory when it has been more important for lawyers to fulfill their professional responsibilities," says William Lee, former co-chairman of Wilmer Cutler Pickering Hale and Dorr. "As a profession, we must ensure that the rule of law that is our fundamental core value is our highest priority and applicable and available to everyone."

Brad Karp, chairman of Paul Weiss Rifkind Wharton & Garrison, expresses a similar sentiment. "This has been a very painful election cycle," he says. "There is absolutely no place in our democracy for disrespecting the rule of law, for disrespecting the democratic process, and for attacking and denigrating individuals based on their gender, race or ethnicity. Such rank prejudice is anathema to the fundamental principles on which our nation was founded. Let us hope that our new president governs in a more inclusive and statesmanlike way than he campaigned."

They were referring to some of Trump's comments during the campaign, when he accused a US-born federal judge of bias because of his Mexican ancestry, called for Hillary Clinton to be sent to prison, suggested that Second Amendment enthusiasts take matters into their own hands if Clinton were elected, claimed that the election was rigged when he was trailing in the polls, and refused to promise that he would accept the election results unless he won.

"As lawyers we pledge an oath to uphold the rule of law," says Theodore Boutrous Jr, the co-chair of Gibson Dunn & Crutcher's litigation group. "We now have a president-elect who has threatened to abridge many of our most cherished civil liberties and constitutional values. It is crucial for lawyers to make clear that we will stand together – both as a deterrent against any effort he makes to do so and as a shield to stop him if he tries."

During the presidential campaign, relatively few lawyers spoke out about Trump's behaviour. One of them was Boutrous. On 12 October, after Trump threatened to sue The New York Times for publishing accounts of women who claimed that he had sexually harassed them, Boutrous reacted on Twitter. He asserted that such a suit would be "utterly frivolous, a flat violation of the First Amendment" and offered to defend the Times if Trump sued. Then, on 22 October, after Trump vowed to sue those women for libel, Boutrous tweeted: "I will represent pro bono anyone Trump sues for exercising their free speech rights. Many other lawyers have offered to join me."

As of early November, Boutrous's second message had been viewed more than 1.5 million times and retweeted more than 12,000 times. The partner, who describes himself as an open-minded Democrat, says that more than 100 lawyers have offered their services.

"The response has been incredible," says Boutrous. "It cuts across politics. Republicans in my firm said they want to help."

One of them is Thomas Dupree Jr, who was a high ranking lawyer in the US Department of Justice under President George W Bush. "I am a conservative Republican," says Dupree, who appeared on Fox News to criticise Hillary Clinton during the campaign, but was not affiliated with the Trump camp. "At the end of the day, defending the Constitution is a conservative value."