Three young women who took part in a public sex romp in an inner-Brisbane street as children watched on will not be charged over the 'vulgar' act.

The women were caught on CCTV cameras on March 3 engaging in lewd sex acts on a James St footpath in Fortitude Valley, in daylight hours.

Police claim they have no reason to charge them, despite the public sex being in full view of elderly couples, parents with prams and nearby hospitality workers.

The sex act lasted about 10 minutes before the police swooped in on the women.

Queensland cops will not be charging three women over a 'vulgar' public sex act in an inner-Brisbane street

But instead of charging the almost semi-naked trio, officers - seen in footage addressing one woman with exposed breasts and the second straddling the third - helped them dress and sent them on their way in an Uber.

Queensland Law Society president, Bill Potts, said laying charges was at the discretion of police.

But he also noted the video evidence would constitute at least a public nuisance offence.

'People are entitled to enjoy their lunch or enjoy the use of public spaces without being forced to watch that type of behaviour,' Mr Potts said.

Queensland Law Society president, Bill Potts, said laying charges are at the discretion of police

According to a Queensland Police spokesman, the officers had 'nothing they could charged the women with.'

'They did not witness what is by definition willful exposure,' The Courier Mail reported.

'You cannot see the women's genitalia, hence they did not witness an offence.'

The police spokeman also said that the police would only investigate if a formal complaint was made.

One man who had witnessed the public romp said it was 'completely vulgar.'

Another witness revealed that he had seen people get charged for lesser crimes, such as public urination.