The law giving government agencies the power to order Internet companies to block material the state deems illegal came into force Thursday.
Ostensibly aimed at protecting children from pernicious content online, the measure allows material to be blocked if officials determine that it includes child pornography, solicits children for porn, encourages drug use or promotes suicide.
A less specific ban on distribution of content that is illegal is also part of the law.
Officials refused to amend the language in the legislation about the government's "blacklist," or registry of illicit material, ignoring recommendations to narrow it from Internet service and content companies and free-speech advocates.
Instead, the current wording leaves the door open to shutdowns of entire websites, even if the offending material is just one of thousands of pages on the site.
At issue is how the law describes the web material in the blacklist. The text doesn't distinguish between the blocking of webpages, IP addresses or domain names, Karen Kazaryan, chief analyst with the Russian Association for Electronic Communications, said Thursday.
The Federal Mass Media Inspection Service — the watchdog within the Communications and Press Ministry — will maintain the blacklist.
Reporters Without Borders condemned the law. "We are forced to conclude that no political will exists to resolve the law's contradictions and to eliminate those that pose threats to freedom," it said in a statement issued Thursday.
It also depicted the regulation as one of "a related series" of measures that have flown through the State Duma in the past half-year, including laws expanding the definition of treason and increasing the scope of blasphemy charges.
"In each of these bills, imprecise language and vague definitions are far too open to interpretation," the human rights group said. It called on Duma deputies to "revise their proposals in light of the fundamental right to freedom of information, which the Russian Constitution and international conventions ratified by Russia guarantee to all citizens."
A working group consisting of government officials and Internet service and content company representatives convened in late September, but the webpage-website distinction wasn't resolved.