President Trump takes part in a forum called Generation Next at the Eisenhower Executive Office Building in Washington on March 22. (Leah Millis/Reuters)

Philip Allen Lacovara is a former president of the D.C. Bar. He served as counsel to the Watergate special prosecutor.

There are many reasons not to represent President Trump in the investigation by special counsel Robert S. Mueller III. But the most common reason offered by prominent defense lawyers — “business conflicts” — is not one of them.

The problem facing many of these highly regarded lawyers is palpable: Taking on Trump as a client may be bad for business. He is notorious for stiffing lawyers (as well as others who have done work for him), and large law firms with the most talented lawyers depend on business from corporate clients, who may dislike Trump or fear tainting their brand if “their” law firm were to defend the president.

But what is good for business may not be in the best interests of the legal profession — or the country.

What distinguishes a profession from a trade is a sense that its goal is higher than merely making a product. At their best, leaders of the bar are willing to risk financial penalties to make the justice system work. That means admirable lawyers — and their law firms — should be prepared to provide counsel to a deeply unpopular client and face the repercussions.

Trump’s efforts to secure and retain good counsel have descended into farce, with a revolving door of lawyers coming and going. We see almost daily reports of prominent defense lawyers, including Republicans, acknowledging that Trump or his intermediaries approached them, only to turn the job down.

For some, this inspires glee. The instinctive reaction is to say that Trump does not “deserve” a first-rate lawyer to help him avoid what we may consider his just deserts. But that reaction is not faithful to the best traditions of the legal profession.

Lawyers are forbidden to undertake new clients if doing so would conflict with the legal interests of existing clients, but that does not seem to be the kind of “conflict” that most lawyers have given in turning down Trump. They use “business conflicts” — code for “the firm’s clients will not like it, and we may lose business.”

This may have a commercial basis, and Trump may be unique among presidents in generating this kind of antipathy. But over many decades, other prominent people and controversial causes have stimulated similar threats to law firms’ business, and leaders of the legal profession have regularly and properly reminded lawyers of their duty to take on the defense of the unpopular.

The principle is enshrined in the American Bar Association’s Model Rules of Professional Conduct, which assures lawyers that representation of a client “does not constitute an endorsement of the client’s political, economic, social or moral view or activities.” Although the rules do not force lawyers to take on unpopular clients, they admonish that lawyers should not turn down appointments unless “the client or the cause is so repugnant to the lawyer as to be likely to impair the client-lawyer relationship.”

Indeed, the proudest hours in the legal profession have come from this tradition, including John Adams’s representation of British soldiers involved in the Boston Massacre. In recent memory, we can look to the legions of lawyers who have brushed aside pressure from corporate clients to represent suspected communists in the 1950s, Vietnam protesters in the 1960s, “boat people” in the 1970s and al-Qaeda suspects at Guantanamo Bay in the early 2000s.

And let us not forget the lawyers who, at significant commercial risk, fought segregation despite opposition from corporate clients. Consider my former boss, Leon Jaworski, who — a decade before taking over the Watergate investigation — was head of one of the largest corporate law firms in still-segregated Texas. At the time, Attorney General Robert F. Kennedy asked Jaworski, as a respected Southern lawyer, to prosecute Mississippi Gov. Ross Barnett (D) for contempt of court after he defied orders to desegregate the University of Mississippi.

Jaworski later said that he was threatened, shunned and scolded by strangers as well as friends for his role in the fight. Many of his Texas business associates broke off their relationships because he took on the assignment. Ten years later, he was equally faithful to the highest traditions of the legal profession when he accepted the responsibility to investigate President Richard Nixon, who had carried Texas during the 1972 election with 66 percent of the popular vote.

Some lawyers may decide that Trump’s practice of disregarding advice from his lawyers would make it pointless to undertake to represent him. But few of the lawyers who have rejected Trump’s overtures have offered this explanation. Respected members of the bar, who have the qualifications to provide counsel to an unpopular figure who desperately needs good lawyering, should not allow actual or potential dissatisfaction from the firm’s corporate clients to distort their own professional decision.