The new National Children's Hospital faces legal action from a renowned US paediatric facility.
The objection concerns controversial plans to call the completed building the Phoenix Children's Hospital.
In a letter to Health Minister Simon Harris, the American hospital of the same name says it has had "troubling feedback" that patients are already confusing the two organisations.
According to the Irish Times, it wants the board to refrain from "leveraging its name, goodwill and earned reputation".