It’s no secret that most class action plaintiffs and defendants usually view each other with great suspicion from across a great divide. (I can’t say all; I have a few good friends among the plaintiffs’ bar, and I think quite highly of several plaintiffs’ lawyers regardless of any substantive disagreements.) What may be surprising, though, is research that shows that this mutual distrust not just a paycheck-induced mental state, but a smart choice for both clients and the lawyers themselves.

At least, that’s what a recent set of experiments conducted by several business professors suggests. Authored by Professors Sandy JapDiana Robertson, and Ryan Hamilton (this one, not this one), The Dark Side of Rapport describes two possible pitfalls for lawyers who develop rapport with the opposing side.

First, lawyers who develop rapport may be more likely to compromise their clients’ interests. This is not necessarily all that surprising. Depending on the client, the lawyers may have longer-term relationships with each other. And a lawyer may justify compromising his client’s interest in all kinds of ways, such as telling himself that the long-term relationship with opposing counsel will benefit future clients, or that the compromise is the only way to get the client at least some of what she wants.

Second, lawyers who develop rapport with each other may be more likely to deceive each other. At first glance, this may seem counterintuitive. If you have a rapport with someone, aren’t you more likely to try to keep their trust?  Aren’t we more inclined to deceive the jerk than the guy with whom we can see eye-to-eye? As it turns out, negotiators will often hide or downplay bad news in order to maintain the rapport that they have.

How did he researchers discover these issues? The experiments were built around a negotiation exercise known as the Bullard Houses case. Bullard Houses is designed for negotiation training. It pits a property seller (who absolutely does not want the property used for commercial purposes) against a hotel developer (who is trying to keep a low profile about its preferred locations). So Bullard Houses is designed to create an impasse; unless, of course, someone either lies or compromises her client’s interests. The authors tweaked the conditions of the exercise in various ways to encourage rapport. (Specifically, they encouraged one group to negotiate face to face instead of by instant-messaging; they had another group engage in team-building exercises; and they "primed" a third group by having them think happy thoughts.) They then looked at how many members of each group resolved the impasse in some way. In general, conditions that encouraged rapport encouraged resolution. (The researchers also tried to prime one group with reminders about duty, ethics, and reputation. It didn’t help.)

So what does this suggest for class action lawyers? The primary lesson may be to maintain a cordial distance from the other side. There’s no reason to unnecessarily provoke opposing counsel, but a conscientious lawyer may remember not to get too chummy, either.

Another implication–peculiar to class actions–is that courts (and defense counsel) may need to be careful of rapport between plaintiffs’ attorneys and clients. After all, rapport works both ways. And there is already some evidence that, where possible, class-action attorneys select plaintiffs that are easier to manipulate.  In a legal sense, the client’s job is to represent the interests of the proposed class. But if the client is more interested in maintaining a rapport with her attorney (either because of the emotional satisfaction, or because that may be the best way to get the attorney to fight for an incentive payment), then the plaintiff may have a strong incentive to compromise the interests of class members she has never met for the interests of the attorney with whom she works.