A new study has shown that blocking access to torrent sites has little to no effect on users, with new avenues for piracy popping up faster than they can be closed.

Like the Hydra of Greek mythology, cutting off the head of a site like The Pirate Bay only causes two more to appear in its place, according to a new research paper by four Dutch academics. The success of BitTorrent programs and torrent-hosting sites seems to be growing exponentially, the study finding hundreds of services around the world.

The study was conducted after the Dutch government ordered two major ISPs to block access to The Pirate Bay; one of the most popular sites for accessing torrents of illegal material. The study found that the ruling had “no lasting net impact on the percentage of the Dutch population downloading from illegal sources.”

The ease with which people can subvert such blocks with simple virtual hosting or anonymous web proxy tools might have been known to the researchers. In their report the authors say: “the economically more relevant question is not whether blocking access decreased the number of visitors, but what the effect of the blocking has on online copyright infringement as a whole.”

The study concludes that: “while a small group of respondents download less from illegal sources or claim to have stopped, there is no lasting net impact on the percentage of the Dutch population downloading from illegal sources, as people learn to use alternatives to The Pirate Bay.”

The study polled 2000 people at the time of the ban and then followed up 6 and 7 months later to look for a shift in torrent use. Somewhat unsurprisingly it found: “Downloading from illegal sources has not decreased since the intervention. In fact, for users of some ISPs the percentage of consumers who downloaded in the preceding six months increased. Approximately 25% of consumers downloaded from an illegal source in the past six months, of which 20-25% decreased their downloading in reaction to the blocking.”

“The percentage of customers that downloaded in the past month increased. Thus, though a small share of downloaders report a decrease in their downloading activities after the blocking, this effect is not reflected in the overall numbers, possibly because there are other consumers who have started downloading from illegal sources.”

A full copy of the report is available online.