Hundreds of protesters have marched through Irish cities after a defense lawyer used an alleged rape victim's choice of underwear to argue that the teenage girl had consented to sex.

The demonstrations in Dublin, Cork, and Limerick followed the acquittal of a 27-year-old man after his lawyer told jurors the teenage complainant "was wearing a thong with a lace front."

The case sparked fury in Ireland, with thousands of women sharing images of their underwear on Twitter and the hashtag #thisisnotconsent in the aftermath of the verdict.

The man, who was acquitted by a jury at Cork's Central Criminal Court on November 5, denied raping the 17-year-old girl in a lane in the city.

Elizabeth O’Connell, the defence counsel, reportedly told jurors: “Does the evidence out-rule the possibility that she was attracted to the defendant and was open to meeting someone and being with someone? You have to look at the way she was dressed. She was wearing a thong with a lace front.”