WASHINGTON — Liberals used to love the First Amendment. But that was in an era when courts used it mostly to protect powerless people like civil rights activists and war protesters.

These days, a provocative new study says, there has been a “corporate takeover of the First Amendment.” The assertion is backed by data, and it comes from an unlikely source: John C. Coates IV, who teaches business law at Harvard and used to be a partner at Wachtell, Lipton, Rosen & Katz, the prominent corporate law firm.

“Corporations have begun to displace individuals as the direct beneficiaries of the First Amendment,” Professor Coates wrote. The trend, he added, is “recent but accelerating.”

Professor Coates’s study was only partly concerned with the Supreme Court’s recent decisions amplifying the role of money in politics.