Online communications law is incoherent and fails to protect victims of abuse from harassment such as “deepfake” pornography, according to a report by the Law Commission.

Commissioned by the Department for Digital, Culture, Media and Sport (DCMS), the study calls for the reform and consolidation of existing criminal legislation dealing with offensive and abusive communications.

Police and prosecutors have to deal with a confusing number of overlapping offences as well as loose or ambiguous terminology such as “gross offensiveness”, “obscenity” and “indecency”, which do not provide sufficient legal clarity, the report says.

About 96% of people aged 16 to 24 use social media, according to the Office for National Statistics. Among all adults, the figure is 66%.

The research by the Law Commission England and Wales follows an announcement by the prime minister, Theresa May, in February in which she declared that abuse in public life had become so severe that it threatened democracy.

One of the guiding principles of the commission’s research has been that the criminal law should provide equal protection against abuse made online or offline.

One contributor to the consultation said: “Online abuse is like domestic abuse in the 1980s. People used to say it was just something that happened. Police didn’t step in on disputes between husband and wife, but every part of society changed when prosecutions started being brought.”

The review looked at deployment of the Malicious Communications Act 1988, the Communications Act 2003 and offences that criminalise threatening and distressing behaviour in the Public Order Act 1986 and the Protection from Harassment Act 1997.

The Home Office estimates that only 3% of malicious communications offences result in a prosecution. “It is not always clear when the expression of an unpopular view or a joke that is considered by many to be in poor taste should cross the threshold into criminal conduct,” the report says

One type of behaviour the Law Commission report identifies as causing particular concern is what is known as “pile on” abuse online.

One respondent, for example, described the experience of being persistently called “you fucking bitch”. She said: “Maybe one off it doesn’t matter, but when you have 500 coming into your inbox, 500 people saying it, maybe you don’t think that.”

At present the criminal law does not treat such abuse as an intense form of harassment. Future reforms could consider whether the conduct associated with “pile on” harassment, such as coordinating and inciting this behaviour, could be more effectively targeted.

The study also examines how effectively the criminal law, such as the Data Protection Act, protects personal privacy online.

The commission questions whether the harm caused by emerging technologies such as deepfake pornography – in which the individuals’ faces are transposed by computer manipulation onto the bodies of naked people – are adequately dealt with by the criminal law.

It also questions whether the law is adequate to protect victims who find personal information, for example about their health or sexual history, spread online.

The report highlights the harm caused to victims of online abuse, including depression, anxiety and feelings of shame, loneliness and distress.

Some but not all deliberately false communications sent with the intention of causing “distress or anxiety” or “annoyance, inconvenience or needless anxiety” may amount to an offence, the Law Commission points out. The threshold at which such matters as “dangerously false health or safety advice” should become reviewed, it suggests.

Professor David Ormerod QC, the law commissioner for criminal law said: “As the internet and social media have become an everyday part of our lives, online abuse has become commonplace for many. Our report highlights the ways in which the criminal law is not keeping pace with these technological changes.”

Responding to the report, the digital minister Margot James said: “Behaviour that is illegal offline should be treated the same when it’s committed online. We’ve listened to victims of online abuse as it’s important that the right legal protections are in place to meet the challenges of new technology.”