Ms O’Brien said she was “in awe” of Nikita Hand and her civil court victory proved to other victims that “you still have a voice”.
The protest was organised by ROSA, a socialist feminist movement, as part of International Day for the Elimination of Violence against Women.
The protesters marched from Dublin city hall, along the River Liffey and to the office of the Irish director of public prosecutions (DPP) to express concern at the failure to take a criminal case against McGregor.
A higher legal threshold applies to a criminal case than a civil case.
In a criminal case, the burden of proof is beyond reasonable doubt, while in a civil case, it is on the balance of probabilities.
‘Women don’t feel safe’
Donna McCarthy, who travelled from County Kerry to attend the protest, said the DPP’s treatment of Ms Hand was “absolutely disgraceful”.
“I think they should have taken her case.
“I think women and girls of Ireland, even if we have won our small cases, we have to fight for the rest of them that didn’t actually get there or are not heard.”
Deirdre De Feu, another protester, said it was important to attend “because women aren’t feeling safe anywhere in the streets or in the public area or at home”.
“So the important thing is that we all come together to support any woman in need.”
Donna Heaney from the survivors’ group Sisi said that victims need to be heard and believed.
“The fact that the DPP weren’t able to prosecute this is huge and I’m so glad there was some sort of justice – it wasn’t enough,” she said.
“So many victims go through the same thing.”
The DPP told Ms Hand in 2020 that there was “insufficient evidence” to bring a criminal case and there was not a reasonable prospect of conviction.
Ms Hand asked the DPP to review the decision, saying she felt she was being treated differently because one of the suspects was famous.
Asked about the DPP’s decision not to prosecute, the outgoing Irish justice minister, Helen McEntee said at the weekend: “We have a very independent system in this country, and I think that’s right.
“I really think it’s important that we respect that independence.”