The footage filmed by Gemma Atkinson

guardian.co.uk

A woman is to challenge the Metropolitan police in the high court, claiming she was handcuffed, detained and threatened with arrest for filming officers on her mobile phone.

Lawyers for Gemma Atkinson, a 27-year-old who was detained after filming police officers conduct a routine stop and search on her boyfriend, believe her case is the latest example of how police are misusing counterterrorism powers to restrict photography.

Atkinson's mobile phone recorded part of the incident at Aldgate East underground station on 25 March, one month after Section 58(a) – a controversial amendment to the Terrorism Act – came into force, making it illegal to photograph a police officer if the images are considered "likely to be useful" to a terrorist.

Atkinson handed the footage, in which an officer can be heard telling her it is illegal to film police and demanding to see her phone, to the Guardian and said she was seeking to challenge the force in a judicial review. The incident was captured on CCTV.

The opening part of the mobile phone clip shows two uniformed police officers searching her boyfriend, Fred Grace, 28, by a wall in the station. Atkinson said she felt that police had unfairly targeted Grace, who did not have drugs in his possession, and decided to film the officers in order to hold them to account.

Seconds later, an undercover officer wearing jeans and a black jacket enters the shot, and asks Atkinson: "Do you realise it is an offence under the Terrorism Act to film police officers?" He then adds: "Can you show me what you you just filmed?"

Atkinson stopped filming and placed her phone in her pocket. According to her account of the incident, which was submitted to the Independent Police Complaints Commission that night, the officer tried several times to forcefully grab the phone from her pocket.

Failing to get the phone, he called over two female undercover officers from nearby. Atkinson said he told the women: "This young lady had been filming me and the other officers and it's against the law. Her phone is in her right jacket pocket and I'm trying to get it."

An argument ensued, Atkinson said, and five police officers – four of them undercover – backed her into an alcove, insisting they had the right to view her phone.

She said she was detained there for about 25 minutes, during which her wrist was handcuffed and a female officer told her: "We'll put you under arrest, take to you to the station and look at your phone there."

A second female officer approached her and said, incorrectly: "Look, your boyfriend's just been arrested for drugs, so I suggest you do as we say."

Atkinson claims the male undercover officer who initially approached her repeatedly threatened her with arrest, stating: "We believe you filmed us and that's against the law so we need to check your phone." When Atkinson protested, the officer replied: "I don't want to see myself all over the internet."

After officers made calls to the police station, possibly for legal advice on the situation, the handcuffs were removed and Atkinson was released.

She said the officers walked away – all but one of them refused to identify themselves to her.

"I felt totally helpless," she said. "I was being restrained and I felt that no one was listening to me. During this whole thing I was saying, 'This is a breach of my civil liberties – you can't do this to me, I've done nothing wrong'."

Atkinson's solicitors, Bhatt Murphy, believe that faulty guidance to officers about how counterterrorism laws apply to photography in public places may have contributed to her treatment.

Last week, after notification from Bhatt Murphy that they would seek a judicial review of Atkinson's case at the high court, the Met released the guidance it gives officers.

The force instructs officers that when searching people under the Terrorism Act, they "have the power to view digital images contained in mobile telephones". It adds that the new offence relating to photographing officers does not apply in normal policing activities.

However, the Met's guidance, which has been criticised by human rights lawyers and the National Union of Journalists, has not been endorsed by the Home Office, which is drafting its own legal advice for police.

The Met's guidance is different to that issued by the National Policing Improvement Agency, which specifically advises that "officers do not have a legal power to delete images or destroy film", and suggests that, while digital images might be viewed during a search, officers "should not normally attempt to examine them".

A Met spokesman confirmed they had received Atkinson's complaint.