File-sharing and copyright infringement have been a bugaboo among lawmakers since internet speeds got fast enough to swap music in the late 1990s. No tactic so far has actually yet stopped audiences from swapping music and movies among themselves, and while some sites and services have been shuttered, another two or three are always ready to pop up. So now a lawmaker is trying a new strategy: appealing to the middlemen who actually move the money.

This week, Senator Patrick Leahy of Vermont (chair of the Senate Judiciary Committee) sent letters to the heads of both Visa and Mastercard (PDF) asking them to pull service from a set of 30 “cyberlocker” cites. His list of targeted sites comes from a report (PDF) issued recently from NetNames and the Digital Citizens Alliance, a group that creates and publishes reports about the nature and volume of online crimes.

“Cyberlockers” are just cloud-storage file hosting services. But unlike workplace-friendly names like DropBox, they’re the ones with a less, shall we say, savory reputation.

“Unlike lawful cloud storage services,” Leahy writes, cyberlockers “exist to unlawfully store and disseminate infringing files around the world.” Basically, they’re where you get and store your shared music, movies, TV, and other media of a not-legally-purchased nature.

“The cyberlockers listed in the report bear clear red flags of having no legitimate purpose or activity,” Leahy continues. Although the report doesn’t find that all of the traffic to the sites it cites is illegal, it did find a very high amount to be. Roughly 80% of the files the survey looked at across the 30 named services infringed copyright in some way. (Including, the report mentions as an aside, the 13% of content that was pornographic.)

The 30 services that the NetNames report looked at all provide “premium” subscription-level service, and those services can be paid for with a credit card. This is where Visa and Mastercard come in. The theory goes like this: if file-hosting sites can’t process payments, they don’t make a profit and can’t keep the lights and servers on.

No profit, no motivation. And if they can’t keep the lights and servers on, then they stop being. And when they stop being, sharing of copyrighted material stops. Confetti ensues.

Visa and MasterCard do prohibit their cards being used for unlawful purposes. Leahy, in his letters, reminds executives of both companies that their predecessors testified to as much before the Senate in 2006.

Since the sites exist for unlawful activity, Leahy’s argument goes, and since Visa and MasterCard don’t support unlawful activity, Visa and Mastercard are both therefore strongly urged to “revisit their policies” and to “ensure that payment processing services offered by [Visa and Mastercard] to those sites, or any others dedicated to infringing activity, cease.”

Leahy has a long history of involvement with copyright protection issues. As TorrentFreak notes, he was the lead sponsor of PIPA — one of the two bills that generated an internet-wide protest — back in 2012.

Senator tells Visa and MasterCard to stop serving “cyberlockers” [Ars Technica]