September 23, 2020


Big copyright owners have apparently had some degree of success in their efforts to flood file-sharing networks with decoy files, thereby frustrating users’ attempts to find copyrighted works. Conventional wisdom is that file-sharing systems will institute some kind of reputation-feedback system to help their users determine which sources tend to offer real files and which tend to offer decoys.

Reputation systems try to mimic the dynamics of real-life reputations, which are a powerful mechanism for inducing cooperative behavior, as anyone who has lived in a small town can attest. The best-known reputation technology is EBay’s, which allows everyone who transacts business with you to give you a score, and which aggregates those scores into a concise summary. EBay users are willing to pay more for an item when it is offered by a seller who has built up a good reputation over time. This system has generally worked pretty well.

If file-sharers had the same incentives as EBay users, we could be pretty confident that reputation systems would work for file-sharing vendors too. But the incentives differ in important ways.

For example, an EBay vendor wants to engage in more transactions, because he profits on each one. A file-sharer, though, doesn’t want to upload too many files, because each upload uses up part of his network resources. A file-sharer suffers if his reputation gets too good, so a reputation system may create a perverse incentive to behave poorly sometimes. Indeed, a group of friends might conspire to trash their own reputations, so as to ensure themselves unimpeded access to each others’ files.

There is also the question of who will do the record-keeping for a file-sharing reputation system. EBay is happy to keep track of the reputation reports for their users, because it boosts EBay’s business. The vendor of a file-sharing system may worry that keeping any kind of record of each transaction between users, and giving any kind of recommendation to users about where to get files, might bring the vendor one step closer to the kind of active participation in infringing transactions that got Napster in trouble.

Despite this, my prediction is that at least some file-sharing vendors will try adopting reputation systems, and that after a few false starts they will find a way to make those systems at least modestly successful to combating decoy tactics. But that’s only a guess – I won’t stake my reputation on it.