Though he was on the court for thirteen years, Menhennitt remains most well known for one particular case, "R v Davidson", commonly known as the "Menhennitt ruling". It was the first legal precedent in Australia concerning the legality of abortion, and Menhennitt ruled that abortion was lawfully justified if "necessary to preserve the physical or mental health of the woman concerned, provided that the danger involved in the abortion did not outweigh the danger which the abortion was designed to prevent." It was later largely adopted by courts in New South Wales and Queensland (with the Levine ruling of 1971 and McGuire ruling of 1986 respectively), and was influential in some other states. Menhennitt's ruling remained the basis for abortion law in Victoria for almost 40 years, until the "Abortion Law Reform Act 2008" (Vic) formally decriminalised abortion.