Klein was born in 1910 in Montreal, Quebec. His parents were real estate agents who immigrated from Hungary. He was one of five children. He was educated at Fairmont High and at Strathcona Academy, and obtained his law degree from Université de Montréal in 1933.
Klein eloped with his late wife, Dorothy Ruby, on New Year’s Eve, 1935. They had two children. He was active in the Jewish community and was a member of the executive council of the Canadian Jewish Congress and a co-chairman of the Israel Bond Organization. His wife, Dorothy, died in 1991.
Klein was drafted as the Liberal candidate in the largely Jewish riding of Cartier when incumbent Liberal MP Leon David Crestohl died suddenly during the 1963 federal election campaign. He served for two terms, in the Parliaments elected in 1963 and 1965. He retired before the 1968 federal election when the riding of Cartier was abolished due to redistribution. During his time in Parliament, he served twice as the Chair of the Standing Committee on Indian Affairs, Human Rights and Citizenship and Immigration.
In 1964, Klein introduced a private member’s bill which would have been Canada’s first hate crimes legislation had it been passed. Bill C-21 proposed the death penalty for anyone who committed murder with genocide in mind and a mandatory 10-year sentence for anyone who, with genocide in mind, caused bodily harm or deliberately inflicted conditions designed to bring about the physical destruction of a group. The bill was intended to “outlaw not only Nazi-type hatred, but all hatred.”. However, it died on the Order Paper when Prime MinisterLester Pearson called the federal election of 1965.
In January 1965, the federal government appointed the Special Committee on Hate Propaganda in Canada, chaired by Maxwell Cohen and including Pierre Trudeau (at that time a law professor at the Université de Montréal) The Committee’s mandate was to study the issue of hate propaganda and make recommendations on legislation. One of the first things the Committee did was to meet with Members of Parliament who were interested in the issue, including Klein, to co-ordinate the work of the committee and the members of Parliament.
In 1966 the Cohen Committee reported in favour of legislation. The Pearson government then introduced a bill to amend the Criminal Code, making it an offence to advocate genocide, similar to Klein’s draft bill. The bill also created an offence of publicly inciting hatred in a way likely to induce a breach of the peace, and a third offence, of wilfully promoting hatred. The government bill took four years to wend its way through Parliament, but in 1970, it was passed by the federal government of Pierre Trudeau, now Prime Minister.