WASHINGTON — Justice Antonin Scalia is known as a consistent and principled defender of free speech rights.

It pained him, he has said, when he voted to strike down a law making flag burning a crime. “If it was up to me, if I were king,” he said, “I would take scruffy, bearded, sandal-wearing idiots who burn the flag, and I would put them in jail.” But the First Amendment stopped him.

That is a powerful example of constitutional principles overcoming personal preferences. But it turns out to be an outlier. In cases raising First Amendment claims, a new study found, Justice Scalia voted to uphold the free speech rights of conservative speakers at more than triple the rate of liberal ones. In 161 cases from 1986, when he joined the court, to 2011, he voted in favor of conservative speakers 65 percent of the time and liberal ones 21 percent.

He is not alone. “While liberal justices are over all more supportive of free speech claims than conservative justices,” the study found, “the votes of both liberal and conservative justices tend to reflect their preferences toward the ideological groupings of the speaker.”