Last month, as 100 Harvard law students gathered for a reception hosted by Paul, Weiss, Rifkind, Wharton & Garrison LLP, the festivities were interrupted by a small group of students waving a banner that read #DropExxon and singing Pete Seeger's "Which Side Are You On?" 

The event, which caught some media interest, signaled a mini-movement. The following month, during a Paul Weiss event for Yale students, another group of protestors unveiled the same banner and chanted similar admonitions. Most recently, a third protest by NYU law students targeted Paul Weiss in New York 

These students are exercised over Paul Weiss' representation of ExxonMobil in climate change matters, including a victory in a case brought by the New York Attorney General alleging the company misled investors about the costs of climate change regulation. Even the Daily News, New York's liberal tabloid, branded the case "dubious." Elsewhere, cities are after ExxonMobil and other companies to pay for the impacts of climate change.

It's not my intent here to argue the merits of these claims one way or another. More to the immediate point are the larger questions these students are raising about the social responsibilities of professional service firms, particularly law firms. 

Originally an environmental activist by profession, I remain strongly supportive of aggressive policies to safeguard the environment. But I am also a trained lawyer, committed to the fundamental principle of zealous representation. As CEO of a communications firm, I have represented many of the major energy companies (though not ExxonMobil, or for that matter Paul Weiss) on historic spills and on their environmental stewardship. I did so zealously and without soul-searching. Everyone deserves representation.

When I listen to the protesters who are now urging law students around the country to refuse to interview at Paul Weiss unless it drops ExxonMobil as a client, I wonder if they understand the difference between a law firm and an NGO. At a simplistic level, there's that pesky old question of a client's right to counsel. I doubt these students would excoriate criminal lawyers for defending rapists and murderers. Energy companies don't deserve as much?

In a press release, a Yale student presumably spoke for the whole movement in saying that "Paul Weiss has no shortage of paying clients to choose from, but is giving priority to a company that is sabotaging humanity's chance to address climate change."

Nicely put, but the problem with such fine differences is that it puts all large law firms as well as their clients on a never-ending tightrope. It means that law firms can represent large corporations only until such time as they too may be "sabotaging humanity's chance to address climate change" or some other unpopular social problem. 

Many of Paul Weiss's peer firms likewise represent the oil industry; Davis Polk and Weil also count ExxonMobil as a client, and in the climate-related lawsuits, O'Melveny also represents ExxonMobil; Gibson Dunn represents Chevron; Wachtell and Latham represent ConocoPhillips; Munger Tolles represents Shell; and Kirkland represents Rio Tinto and Total. 

Other peer firms represent the coal, aviation and automotive industries, all of which have large carbon footprints. It's obviously impossible for either law firms or corporations to do business in an environment where, ultimately, everyone deserves to be disqualified.

An additional irony here is that, of all the great corporate law firms, none has been more closely identified with liberal values. Paul Weiss is the firm that in 1954 worked with Thurgood Marshall in representing Oliver Brown in Brown v. Board of Education, opening the door to the desegregation of our nation's public schools, and Edith Windsor in Windsor v. United States, establishing a constitutional right to same-sex marriage. 

The firm's partners have included the likes of Adlai Stevenson, Arthur Goldberg, Arthur Liman and Ted Sorensen. Today, the firm is spearheading high-impact challenges of Trump administration policies taking aim at immigrant families and state laws infringing a woman's right to access a safe, legal abortion. The firm is also leading national anti-gun violence and voter protection efforts. If the protesters can't imagine working for this law firm, where can they possibly work? 

Career issues are the most interesting aspect of this controversy. In a recent class at Harvard, Professor Charles Nesson led a discussion of the Paul Weiss situation in which, says Nesson, students largely approved of the protest and yet were wondering if the participants have harmed their careers. These students seem to be really wrestling now with how to justify a career in Big Law, given their principles. Hardly a new concern, but if the Paul Weiss protests accomplish nothing else, refreshing the discussion can only be beneficial. 

Harvard, Yale and NYU may be the three ripest hunting grounds for corporate law firms, and most of the students at those law schools are presumably thinking hard about going into Big Law. It's not just greed or careerism. They have huge college loans to pay off. And they naturally want to be impactful in their work in ways that the resources of a big firm can make happen. As such, these students do indeed face a choice, but I only hope they understand exactly what that choice is.

For most law school graduates, it is not a choice between Paul Weiss and any other megafirm where they'll be breathing the same air—where hundreds of partners are representing thousands of businesses of every stripe and variety, political or otherwise. 

The real choice is between a career in Big Law versus much smaller law firms where they'll represent a much narrower clientele, firms where the ideological boundaries are often well-defined and inviolable. Of course, in making that choice, they will want to remember that those much smaller firms pay much smaller salaries.

But I bet they already know that.

Richard Levick (@richardlevick) is chairman and CEO of LEVICK, a global communications and public affairs agency specializing in risk, crisis, and reputation management. He is a frequent television, radio, online, and print commentator.