Camille Elies is used to being stopped by the police.

“I don’t know what it is, whether it’s because I’m a guy with long hair or what, but it happens often,” the 19-year-old from Wollongong, south of Sydney told Guardian Australia this week.

So, when a female police officer approached him and a friend while they sat in their car at the Lost Paradise music festival in December last year, he wasn’t too worried at first.

“I knew I didn’t have anything on me, no drugs or anything, so it was no problem,” he says.

“But then the dog started sniffing around the car and she started saying ‘you look a bit nervous mate, you look nervous, if you have drugs on you then you might as well tell me now or I’ll take you to the strip-search tent and we’ll find them that way’.”

Elies says the officer started recording him using her body-worn camera. While he continued to deny he had any drugs, she continued to press him on why he looked “nervous”.

Camille Elies, 19, of Wollongong, who was strip-searched at the Lost Paradise festival in 2018.

“I said, ‘because you are interrogating me and you have the dog there’. She was being so rude about it as if I had done something wrong already,” he says.

Elies was eventually strip searched in a makeshift tent. Two male officers instructed him to lift his shirt, drop his pants and hold on to his genitals while they “walked around” him.

“I was a bit shook up,” he says. “I don’t know. I just, yeah, I was shook up by it to be honest.”

The experience Elies describes is common in New South Wales, where thousands of people are strip searched by police each year. Many of them take place at music festivals and about a quarter follow an indication by a drug dog. In about two-thirds of cases, nothing is found.

Despite that, the number of strip searches has increased almost 20-fold in the past 12 years – from 277 times in the 12 months to 30 November 2006 to 5,483 in 2018 – and police have steadfastly defended their use. This week the police minister, David Elliott, insisted he “would want” police to strip search his children if they were suspected to be in possession of drugs.

Those comments came after Guardian Australia revealed that in the past three years police in NSW have strip searched 122 girls, including two 12-year-olds. One woman, Madz Piper, described a potentially illegal search that occurred in 2011 when she was 15 in which, she says, an officer “grabbed” her bra and “jiggled it”.

Then, on Friday, the NSW deputy coroner released the findings of her inquest into the deaths of six young people from MDMA toxicity at music festivals across the state.

Besides recommending a pill-testing trial in NSW and the complete scrapping of the use of drug-detection dogs at festivals, Harriet Grahame said strip searches should be dramatically curtailed to only being used in cases of suspected supply.

Her published findings revealed that in the 2018-19 financial year, 91% of strip searches were conducted on suspicion the person was in possession of drugs. She noted that meant the search was often being conducted for an offence that carried a punishment equivalent to a traffic infringement.

The “wholesale practice of strip searching young people” was of “grave concern”, Grahame said.

“We know strip searches are causing great harm to the community and now we have the deputy state coroner confirming that this invasive practice is having a devastating impact on young lives,” Sam Lee, the head of police accountability at the Redfern Legal Centre, said on Friday.

This invasive practice is having a devastating impact on young lives. Sam Lee, Redfern Legal Centre

“The proposed changes recommended by the deputy coroner are far from radical, but merely reflect parliament’s original intent that such an invasive procedure be only utilised in the most exceptional of legal circumstances.”

Grahame also revealed the NSW police had sought to stop her considering strip searches as part of the inquest. A submission from the commissioner, Mick Fuller, asserted the evidence did not “establish a sufficient link between the deaths under investigation and the police practice of strip searching”.

Grahame rejected that and, following the publication of her findings on Friday, Fuller released a statement saying he “strongly defended” against the suggestion police were “implicit” in the deaths.

The use and legality of strip-search powers in NSW has been placed under increased scrutiny since the Law Enforcement and Conduct Commission held public hearings for its investigation into the potentially illegal strip search of a 16-year-old girl at a 2018 music festival.

During the inquiry the LECC’s commissioner, Michael Adams QC, said he was considering whether the practice of making people squat during a search was legal.

“But squatting is not the only problematic area in strip searches that requires greater clarification,” he said.

Under the Law Enforcement (Powers and Responsibilities) Act, or Lepra, police in NSW are allowed to conduct a strip-search outside a police station if the “seriousness and urgency of the circumstances” make it necessary.

Critics have long argued that “broadly defined” threshold fails to give police clear guidance on when a strip-search should be carried out.

On Thursday, Labor’s shadow police minister, Lynda Voltz, told Guardian Australia she believed the act was not specific enough and as a result the police interpretation of when a search was justified was “very loose”.

During the LECC inquiry, Adams asked a police officer under what circumstances – apart from a suspicion someone was hiding drugs in a body cavity, which police are not allowed to search – it would be urgent for an officer to conduct a strip search at a music festival.

“I can’t think of any, actually,” the officer replied before admitting that all 19 of the searches he conducted at the 2018 Splendour in the Grass festival may have been illegal.

Madz Piper, 23, with her boyfriend. Piper was 15 when she was subjected to a potentially illegal strip search. Photograph: Supplied

Grahame added her own voice to that point in her findings, saying it was likely that searches are being conducted “unlawfully”.

“Given the number of times that searches occur when there is no emergency or risk of serious harm, one can only assume that many searches are conducted unlawfully including many which occur at music festivals,” she wrote.

Also subject to scrutiny is the basis on which a search is executed. In NSW, a positive detection from a dog does not constitute the legal criteria for conducting a strip search.

But the LECC heard evidence that officers used indicators such as a person’s nervousness following the indication from the dog, like in Elies’s case, to form their suspicion.

That, experts say, is too shallow a basis on which to form a reasonable suspicion because nervousness is a natural reaction to an interaction with a drug dog.

Peta Malins, a lecturer in criminology and justice studies at the RMIT University in Victoria, this year published a study on the emotional impact of drug dog detections and strip searches.

“Everyone I spoke to who had been stopped by police as part of a drug dog detection reported really quite significant embodied responses about fear and anxiety coming up for them in that exchange,” she told Guardian Australia.

“Hands shaking, sweating, heart rate increasing. Even if they knew they’d done nothing wrong and had no drugs, they still felt really anxious and fearful in that encounter.

“So it’s really problematic that police might be relying on nervousness as an indicator about whether to search someone or take them aside for strip searches.”