A judge has reserved judgment in the Commercial Court this week regarding the N86 road between Camp and Dingle.
An Taisce challenged planning approval for a €65 million road widening scheme in West Kerry.
The environment and heritage group wants a decision by An Bórd Pleanála that gave approval for works on parts of the N86 road quashed.
The scheme proposed by Kerry County Council seeks to improve the road from Dingle to Annascaul and from Gortbreagoge to Camp.
An Taisce says the route is renowned for its scenic quality and heritage.
Mr Justice Robert Haughton will most likely deliver his verdict in the next term.