RTE is reporting that People Before Profit TD Paul Murphy has commenced defamation proceedings against Fine Gael presidential candidate Heather Humphreys.
The case relates to comments made by Ms Humphreys in a debate on RTÉ Radio One's This Week programme last Sunday.
Ms Humphreys commented on Mr Murphy's role in an anti-water charges protest in Jobstown in Tallaght in November 2014.
Mr Murphy was one of six men charged with the false imprisonment of the then Tánaiste Joan Burton and her assistant Karen O'Connell in their car on 15 November 2014.
All six were acquitted of the charges by a jury at Dublin Circuit Criminal Court in 2017.