STRASBOURG, France (AP) — Europe’s human rights court handed a partial victory Thursday to civil rights groups that challenged the legality of mass surveillance practices exposed by American whistleblower Edward Snowden.

The European Court of Human Rights ruled that some aspects of British surveillance regimes violated provisions in the European Convention on Human Rights that are meant to safeguard Europeans’ rights to privacy.

Specifically, the court said there wasn’t enough independent scrutiny of processes used by British intelligence services to sift through data and communications intercepted in bulk.

The ruling cited a “lack of oversight of the entire selection process” and “the absence of any real safeguards.”

But the ruling wasn’t all bad for British spies. The court said “it is satisfied” that British intelligence services take their human rights convention obligations “seriously and are not abusing their powers.”

Civil liberties campaigners that brought the case hailed the judgement as a landmark against mass surveillance.

Silkie Carlo, director of Big Brother Watch, said the ruling “vindicates Mr. Snowden’s courageous whistleblowing.”

“Under the guise of counter-terrorism, the U.K. has adopted the most authoritarian surveillance regime of any Western state, corroding democracy itself and the rights of the British public,” Carlo said in a statement. “This judgment is a vital step towards protecting millions of law-abiding citizens from unjustified intrusion.”

Dan Carey, a lawyer for the complainants, said: “There needs to be much greater control over the search terms that the government is using to sift our communications.”

Britain has changed its surveillance laws since the legal challenge began, passing new legislation that the government says has more privacy safeguards. But rights groups say it is still far too intrusive.