Throughout the 1950s, 1960s and 1970s, MacBride worked for human rights worldwide. He took an Irish case to the European Court of Human Rights after hundreds of suspected IRA members were interned without trial in the Republic of Ireland in 1958. He was among a group of lawyers who founded JUSTICE—the UK-based human rights and law reform organisation—initially to monitor the show trials after the 1956 Budapest uprising, but which later became the UK section of the International Commission of Jurists. He was active in a number of international organisations concerned with human rights, among them the Prisoners of Conscience Appeal Fund (trustee).