The question at the heart of one of the biggest Supreme Court cases this year is simple: What constitutional rights should corporations have? To us, as well as many legal scholars, former justices and, indeed, drafters of the Constitution, the answer is that their rights should be quite limited  far less than those of people.

This Supreme Court, the John Roberts court, seems to be having trouble with that. It has been on a campaign to increase corporations’ legal rights  based on the conviction of some conservative justices that businesses are, at least legally, not much different than people.

Now the court is considering what should be a fairly narrow campaign finance case, involving whether Citizens United, a nonprofit corporation, had the right to air a slashing movie about Hillary Rodham Clinton during the Democratic primary season. There is a real danger that the case will expand corporations’ rights in ways that would undermine the election system.

The legal doctrine underlying this debate is known as “corporate personhood.”

The courts have long treated corporations as persons in limited ways for some legal purposes. They may own property and have limited rights to free speech. They can sue and be sued. They have the right to enter into contracts and advertise their products. But corporations cannot and should not be allowed to vote, run for office or bear arms. Since 1907, Congress has banned them from contributing to federal political campaigns  a ban the Supreme Court has repeatedly upheld.