Treitel was born in Berlin in 1928. As a young Jewish boy, he experienced Nazi persecution at first hand, and in 1939 was forced to flee to the UK with his brother on the Kindertransport. Although he found safety in the UK, his early years as a refugee were difficult and he had to fight for the chance to continue his education at a grammar school.
In 1946, Treitel won a scholarship to Magdalen, where he read for the BA and BCL. After a brief period as a lecturer at the LSE, Treitel took up a Fellowship at Magdalen in 1954, remaining there until 1979 when he was appointed to the Vinerian Professorship of English Law and moved to All Souls. Although he retired from the chair in 1996, he remained active for many years, continuing to work in the Codrington Library on a regular basis and to have lunch at All Souls on a Wednesday and his beloved Magdalen on a Friday. He was knighted in 1997.
Few contemporary lawyers have played as big a role in developing the law, primarily because his writings are the product of careful and principled thought founded on an exact and honest analysis of the existing case law.
Outside the law, Treitel was a member of the Council of the National Trust from 1984 to 1993, and a trustee of the British Museum from 1983 to 1998, a role which gave him great pleasure. He was well-known for his love of the novels of Jane Austen, even writing an article about her treatment of the law, which appeared in the centenary issue of the LQR. He once explained that he read some Jane Austen every day, taking the novels in strict rotation in order to avoid the strong temptation only to read Emma.
Although Treitel will be remembered principally for his great scholarly achievements, he was a modest and kindly person, always ready with a word of wise advice for younger colleagues expressed in the mildest terms. He will be much missed.