Mr Justice Henchy was an alumnus of University College Galway and University College Dublin. He was called to the Bar in 1943 after studying at the King’s Inns and took silk in 1959.

He lectured in legal history, Roman law and jurisprudence at UCD while practising at the Bar before being appointed to the High Court in 1962.

He heard many personal injury cases and notably presided over the Arms Trial in 1970 after Mr Justice Aindrias Ó Caoimh withdrew because of accusations of bias. The selection of Mr Justice Henchy in the circumstances is a sign of his integrity.

Mr Justice Henchy was elevated to the Supreme Court two years later in 1972, one decade after his appointment to the High Court.

He displayed humanity in his Supreme Court judgments, including in McGee v Attorney General. That case led to the cessation of the ban on the importation of contraceptives.

Mr Justice Henchy’s judgment highlighted his natural empathy with the plaintiff, a 27-year old mother of four whose life would be endangered if she got pregnant again. He said that the statutory prohibition of contraceptives “condemn[ed] the plaintiff and her husband to a way of life which, at best, will be fraught with worry, tension and uncertainty that cannot but adversely affect their lives”.

Mr Justice Henchy was also ahead of his time in some respects. In Norris v Attorney General, a 3–2 majority of the Supreme Court upheld the legal provisions which criminalised homosexuality in the Republic of Ireland. Mr Justice Henchy and Mr Justice Niall McCarthy were the two dissenting judges.

In 2020, Mr Justice Gerard Hogan, now a Supreme Court judge, said in a lecture at NUI Galway that Mr Justice Henchy “delivered a magnificent dissent” in Norris. “One way or the other, the impugned provisions [criminalising homosexuality] seem doomed to extinction,” Mr Justice Henchy noted, showing great foresight. Same-sex sexual activity was decriminalised 10 years later in 1993.

Near the end of his time on the Supreme Court, Mr Justice Henchy gave judgment in the significant case of Crotty v An Taoiseach in 1987. There, the court held that a constitutional amendment was required before Ireland could ratify the Single European Act, subsequent EU treaties and substantial changes to them.

Mr Justice Henchy retired from the Supreme Court in 1988 and became the first chairman of the Independent Radio and Television Commission that year.

A celebrated legal mind, Mr Justice Henchy was awarded an honorary doctorate by Trinity College Dublin in 1990 and another one by the NUI Galway in 1999.

Mr Justice Hogan paid tribute to Mr Justice Henchy in the Irish Jurist as someone who was able to correctly “identify the future path of the law and to persuade others — and, indeed, society at large — to follow it”.