Jacob ben Judah Hazzan was a 13th-century Jewish legal codifier based in London, England.
In 1287 Jacob wrote Etz Chaim a ritual code in two parts, containing 646 sections respectively, dealing with the whole sphere of Halakah, and following in large measure Maimonides in the Mishneh Torah, though Jacob utilized also the Halakot Gedolot, the Siddur of Amram Gaon, and the works of Moses of Coucy, Alfasi and the tosafists.
He quotes, furthermore, Isaac ben Abraham, Moses of London and Berechiah de Nicole (Lincoln).
[1] The Etz Chaim still exists in a manuscript which formerly belonged to Johann Christoph Wagenseil and is now in the Rathsbibliothek in Leipzig.
[1] A partial edition was published by Hermann Adler in Leipzig, 1896.