The phone rings, you pick it up, and the caller identifies himself as an officer of the court. He says you failed to report for jury duty and that a warrant is out for your arrest. You say you never received a notice. To clear it up, the caller says he'll need some information for "verification purposes" — your birth date, Social Security number, maybe even a credit card number.

This is when you should hang up the phone. According to the FBI, it's a scam.

"A municipal, magistrate's or county clerk of court will never ask for information other than demographics pertinent to court, such as date of birth, sex and race," said Union County Clerk of Court Brad Morris. "There would never be a reason for us to want to know a Social Security number and certainly not a credit card number. The whole purpose of a jury summons is to identify someone and have them come to court. A clerk doesn't need a Social Security number to achieve that and if anyone hears of this, I ask them to give me a call."

Jury scams have been around for years, but have seen a resurgence in recent months, the FBI said. Communities in more than a dozen states have issued public warnings about cold calls from people claiming to be court officials seeking personal information. As a rule, court officers never ask for confidential information over the phone; they generally correspond with prospective jurors via mail.

The scam's bold simplicity may be what makes it so effective. Facing the unexpected threat of arrest, victims are caught off guard and may be quick to part with some information to defuse the situation.

"They get you scared first," says a special agent in the Minneapolis field office who has heard the complaints. "They get people saying, 'Oh my gosh! I'm not a criminal. What's going on?'" That's when the scammer dangles a solution-a fine, payable by credit card, that will clear up the problem.

With enough information, scammers can assume your identity and empty your bank accounts.

"It seems like a very simple scam," the agent adds. The trick is putting people on the defensive, then reeling them back in with the promise of a clean slate. "It's kind of ingenious. It's social engineering."