Prohibiting dark web browser Tor is "technologically infeasible," a Parliamentary group has claimed.
The Parliamentary Office of Science & Technology (POST) has released a guidance note on the popular dark net browser used by millions to suggest any attempts to block it would prove useless.
It read: "Banning online anonymity systems altogether is not seen as an acceptable policy option in the UK. Even if it were, there would be technical challenges."
The advisory office pointed to China's 2012 attempts to outlaw the browser, which wraps user activity under several layers of encryption to hide their IP addresses.
In that case, Tor Project Inc, the body responsible for the browser, just introduced secret entrance nodes leading into it, which are nearly impossible to block.
The note added: "Computer experts argue that any legislative attempt to preclude THS (Tor Hidden Services) from being available in the UK over Tor would be technologically infeasible."
Tor has earned a reputation as an online haven for drug dealers and other criminals thanks to the high profile battle between the FBI and darkweb drug marketplace Silk Road.
But the POSTnote, which provides a briefing on Tor for MPs to understand the issues, rather than as a way to guide policy, added that only a small proportion of Tor activity is criminal.
Tor also benefits whistle-blowers, who can protect their identities while sounding the alarm over unscrupulous practices, the note explained, as well as giving open internet access to people living under oppressive regimes.
Even the NSA has been unable to identify Tor users in any meaningful way, only being able to de-anonymise small groups of users with a lot of highly-skilled manual effort, it added.
And the note suggested that giving drug dealers a secure online space in which to operate can cut street crime.
The note, published yesterday, comes after Prime Minister David Cameron suggested banning secure, encrypted messaging services that security services cannot crack.
Liberal Democrat MP Julian Huppert hit out at Cameron's proposal at an election-themed debate last month, saying such a move would damage the UK's export business.
"If you knew that any British product necessarily had a security service's back door in, no bank would buy it, no business would buy it. It would be catastrophic for a lot of these businesses," he said.
