Morgan Pietz, one of the lawyers who wrapped "copyright troll" Prenda Law in a whirl of judicial sanctions, has set his sights on a new target: Rightscorp.

In a class action lawsuit (PDF) filed on Friday, Pietz says the copyright enforcement company made illegal, harassing robo-calls to his clients, who were accused of illegal downloading. The lawsuit says that Rightscorp broke the Telephone Consumer Protection Act (TCPA), a 1991 law which limits how automated calling devices can be used.

The suit also claims that Rightscorp met the legal definition of a "debt collector" but made harassing phone calls and didn't abide by federal or California debt collection laws. Rightscorp company managers, including CEO Christopher Sabec and COO Robert Steele, and Rightscorp's clients are all named as defendants in the lawsuit.

Violations of federal debt collection laws can result in damages of $1,000 and include provisions for paying attorneys' fees in successful cases. TCPA violations can cost $500 per incident, and that can be tripled if the violations were willful.

In an interview with Ars, Pietz says he doesn't know how many violations have occurred. But he says just one of his named plaintiffs was subject to enough illegal phone calls to add up to tens of thousands of dollars in damages.

"They robo-called Jeanie Reif's cell phone darn near every day for a couple of months," Pietz said. "And there could be thousands of members of this class."

If a judge agrees with Pietz that the phone calls were harassing and illegal, Rightscorp could be on the hook for many millions of dollars. That's a lot more money than Rightscorp actually has—the company has lost $6.5 million since its inception in 2011, and its stock price hovers near all-time lows.

The wild card in Pietz's case are the defendants not yet named: John Does 1-10. Those Does are Rightscorp's clients, who Pietz says are liable for Rightscorp's TCPA violations. If Pietz and his clients win big against near-bankrupt Rightscorp, there's a possibility that the enforcement company's marquee music clients—including BMG Rights Management and Warner Brothers—could end up holding the bag.

Calls from "Yaddy" and "Marina"

The lawsuit, filed in Los Angeles federal court on Friday, has two named plaintiffs: Karen J. Reif, who goes by her middle name Jeanie, and Isaac Nesmith.

Reif is a Charter Communications subscriber who lives in Saginaw, Michigan. She called Rightscorp in April of this year after she got a "settlement offer" consisting of an e-mail from Rightscorp, forwarded to her by Charter.

Starting around July, she started getting continuous calls from Rightscorp to both her home phone and her cell phone. Some of the calls were from people, including a woman who identified herself as "Yaddy." Many were automated with what sounded like "an artificial or pre-recorded voice."

According to the suit, Rightscorp left Reif a voicemail in September, saying:

This is an urgent message from Rightscorp regarding your Internet account. We have evidence that one or more of our clients’ copyrighted materials has been illegally distributed through your Internet connection in violation of U.S. Federal Law 17 U.S.C. 106. To settle this urgent matter you can reach one of our agents by pressing any number on your phone keypad now. Or, you can call us at 888- 851-3801 between 8am and 8pm Pacific Standard Time. This urgent message is from Rightscorp.

By late September, she was getting one robo-call per day, the lawsuit states.

Pietz says he's called Rightscorp personally about Reif's case and has been unable to get any details about the infringement accusations against her. He followed up via e-mail. "I asked for the documentation Rightscorp supposedly has substantiating the copyright claims against Ms. Reif," Pietz said. "I am still waiting."

Nesmith, who lives in Riverside County, California, is a customer of a smaller ISP called Greenfield Communications. He was first contacted by Rightscorp in September, when he received a letter to his home address accusing him of downloading two "tracks," without identifying the tracks or who owned them.

That was followed up by repeated phone calls from "Marina" at Rightscorp, who identified herself as “the DMCA agent who is handling your unsettled copyright infringement case." One voicemail from "Marina" went as follows: