The law was designed to prevent children from accessing pornographic content but some fear it would worsen the issue.
ADVERTISEMENTWebsites providing pornographic content will from April be legally required to verify the age of Britain-based visitors.
The "Digital Economy Act 2017" law was passed in an effort to prevent underage internet users from accessing pornographic content but critics have condemned it as infringing on civil liberties and say it is likely to worsen the problem.
Euronews explains the law and some of the controversy around it:
Who decides if the content requires age-verification?
The government has appointed the British Board of Film Classification (BBFC) as the age-verification regulator. The BBFC is an independent regulator that gives films and other commercial video content — streaming services, etc — age ratings.
They will be carrying out spot checks on websites to ensure they comply with the rules. If they are not compliant, the BBFC has been given a number of enforcement powers including instructing internet service providers to block them and handing out hefty fines.
How does age-verification work?
Websites will have to implement an age-verification system from a recognised provider although the BBFC has not yet released its list.
A well-known provider is AgeID, which is owned by MindGeek. The privately-held Canadian company owns several pornography websites including Pornhub, RedTube and YouPorn.
These age-verification companies will demand consumers verify their age by using a phone number, credit card, passport or driving licence.
Will it actually be effective?
As the BBFC states on its website "age-verification is not a silver bullet. Some determined teenagers will find ways to access pornography."
The law also only applies to websites on which "pornographic material makes up less than a third of the content." That means social media platforms are likely to be exempt, so underage users of these sites will still be exposed to pornographic content.
According to the not-for-profit US National Center on Sexual Exploitation, Twitter "hosts vast quantities of hardcore pornography and facilitates prostitution and sex trafficking."
What's the criticism?
The Open Rights Group, a UK-based organisation working on digital rights and freedom of expression, criticised the appointment of the BBFC as the regulator in charge of the regulation.
"We doubt that it is in a good position to judge the proportionality of blocking; it is simply not set up to make such assessments. Its expertise is in content classification, rather than free expression and fundamental rights assessments," it said in a blog post.
Anyone wishing to contravene the system will also be able to use a VPN, critics have pointed out.
Writer and journalist Ian Dunt said this would lead to "a massive chunk of online traffic" going underground, and "worsening the problems which do exist with this content and making authorities' lives harder."
Some also fear that providing personal data to access porn could leave people vulnerable to blackmail and humiliation if hackers target the age-verification systems.
Back in 2015, the dating website for people already in relationships, Ashley Madison, was hacked and data, including user details, leaked online. At least one person was reported to have committed suicide after his name was released.