The high court has agreed that a full legal challenge can be brought against a police stop-and-search power alleged to be used in a racist way against African-Caribbean people.

The challenge follows officers stopping and searching a 37-year-old woman with no convictions, after they claimed she was holding onto her bag in a suspicious way.

The woman, Ann Roberts, ended up being held down by officers on the floor in front of other people, handcuffed and taken to a police station where she was wrongly accused of being a class A drug user and placed on a treatment programme under the threat of arrest if she failed to attend.

Roberts was stopped under section 60 of the 1994 Criminal Justice and Public Order Act, brought in to tackle illegal raves. The power allows police to stop and search people without having a reasonable suspicion they are involved in criminality.

Roberts, a special needs assistant, argued that a disproportionate number of black Londoners are searched in violation of article 14 of the European convention on human rights, which bans discrimination.

Her lawyers say statistical evidence implies that a black person is more than nine times more likely to be searched than a white person. They go on to say section 60 is "incompatible" with three articles of the convention: 14, 5, which protects the right to liberty and security, and 8, which protects the right to private and family life.

Police say section 60 is a valuable tool which has been used to tackle areas plagued by violence.

On 9 September 2010 Roberts was on a bus when an inspector found she had insufficient money for her journey on her prepaid Oyster card.

Police were called when she could not produce identity documents.

According to her lawyers, she was searched under section 60 after a police officer took the view she was holding on to her bag in a manner that suggested she had something to hide.

She was told the area she was in was a "hotspot" for gang violence and the possession of knives. Few, if any, acts of gang violence are committed by married women in their mid 30s.

Roberts asked to be searched in a police station rather than in public in case it was seen by young people with whom she worked.

Police refused and when they tried to seize her handbag a struggle followed which led to officers restraining her on the floor.

Three bank cards with different identities were found in her bag. She explained they were in her name, her maiden name – having recently married – and her son's name.

She was told she was being arrested on suspicion of fraud and taken to Tottenham police station.

She was subjected to a drugs test which she was told showed small amounts of crack cocaine, but a later test showed she was clear.

After being put in a cell, she was interviewed and told she was no longer suspected of fraud but was being detained on suspicion that she had obstructed a police search.

Later a caution was administered for obstruction.