It's safe to presume that many of the petitions these groups threw their weight behind might have been granted without them. Still, empirical studies show a link between filing a cert-stage amicus brief and getting a case heard. In a 1988 study, political science professors Greg Caldeira and Jack Wright of Ohio State University controlled for the "full array" of well-known influences on the court's decision to hear a case—like a split in the lower courts or the participation of the U.S. solicitor general—and found that early-bird amicus briefs "substantially increase" the likelihood that a case will make the court's docket. The chief deputy clerk of the court has even said that amicus briefs are one of four explicit factors the court weighs in deciding whether to grant a case. (The others are the Supreme Court's jurisdiction to hear the case, lower-court conflicts, and the presence of competing petitions on the disputed legal issue.)
If early-bird amicus briefs can alter the character of the Supreme Court's docket, why don't liberal groups come up with more of them? Pro-business groups may have more money to pay for the briefs (which, after all, lawyers are paid to write). Perhaps the rise of specialized Supreme Court practices in major law firms means that more lawyers are on the lookout for work that will benefit their big-business clientele. It is likely, too, that the conservative groups want to get as many cases as they can before this Supreme Court because it's increasingly viewed as not just conservative, but business- friendly.
The ACLU has made an "organizational decision not to file cert-stage amicus briefs, except in extraordinary circumstances," according to Legal Director Steven Shapiro, as an "allocation-of-resources decision." Instead, the ACLU files amicus briefs in 12 to 15 cases a year once the court is deciding between the parties (as opposed to deciding whether to take case). But by that point, research suggests, the briefs' influence is diminished.
Some liberal groups may be trying to keep a low profile on cases that matter to them but that they think they'll lose (though Shapiro says that's not the ACLU's thinking). If that's the concern, should liberal advocates focus on filing briefs in opposition to cert to keep the current Supreme Court away from the cases they see as stinkers? In fact, only one brief of 270 filed by the top 16 amici opposed the taking of a case. And perhaps that's because such a strategy is ill-advised. The Caldeira and Wright study shows that the chances of a case being heard by the court increase with the number of amicus briefs filed, whether or not they recommend or discourage granting the case. In fact, amicus briefs in opposition to cert significantly increase the chances a case will be granted cert. The content of the briefs appears to matter much less than their presence.
But that's no justification for liberal groups to sit on their hands. They can find areas of law in which this Supreme Court (in particular, Justice Kennedy) is likely to side with them. See recent decisions on immigration, the death penalty, the environment, and gay rights. Even in less-friendly territory, they can find petitions presenting questions and fact patterns more favorable to their side and then tell the court why those cases would be better vehicles to decide an issue than cases being pushed by their conservative counterparts. (The National Association of Criminal Defense Lawyers used this move in the famous case on criminal sentencing, U.S. v. Booker.)
The point is that if liberal groups must play defense, they should play smart defense. Staying silent on the sidelines, we know, just doesn't work. A case is won or lost on the merits, but a cause may be lost long before.