A law against taking intimate photos underneath women's clothes without their consent came into force in England and Wales on Friday, a change campaigners hailed as a "crucial step forward".
Gina Martin, who campaigned for the new legislation after she was a victim of so-called upskirting, said she was delighted that other women would be able to prosecute offenders and she hoped her campaign had raised awareness of the crime.
"It feels fantastic," she told the Thomson Reuters Foundation.
"Previously there was no consequences for this - I think societally and in law because people were not expecting to see anyone doing it - and now they are, so I really hope it will act as a really good deterrent."
Already a punishable crime in Scotland, Australia and New Zealand, upskirting was not previously a specific offence in England and Wales.
Martin launched a petition to make it one after she spotted two men taking photos of her crotch at a music festival in 2017, but police declined to prosecute as the image was not graphic.
Her campaign led to the government supporting a bill to close loopholes in the law that had previously meant some voyeuristic photographs taken without consent were not illegal.
The two new laws criminalise taking 'upskirt' images where the purpose is to obtain sexual gratification, or to cause humiliation, distress or alarm.
Those convicted face up to two years in prison and may also be placed on the sex offenders register.
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Justice officials have said the laws will also cover paparazzi who are caught taking intrusive images.
Police and prosecutors have been given updated guidance to ensure the new law is enforced, with Martin urging those who experience or witness the crime to report it.
"We have always been clear – there are no excuses for this behaviour and offenders should feel the full force of the law. From today, they will," said Justice Minister Lucy Frazer.
"By taking decisive action and working closely with Gina Martin and other campaigners, we have ensured more people are protected from this degrading and humiliating practice."
The law change was also welcomed by women's groups, with charity Women's Aid hailing it as "a crucial step forward in tackling sexism and misogyny" in a statement posted on Twitter.