Philip Mechem earned his bachelor's degree from Stanford University in 1922, and legal degrees from University of Colorado and University of Chicago in 1922 and 1926. His father, Floyd Mechem, was also a law professor. He taught law at University of Idaho, University of Chicago, University of Kansas, and Washington University in St. Louis before joining the faculty at University of Iowa College of Law in 1930.
He was served as a professor at Iowa from 1930 to 1948. During World War II, he left Iowa to work in the U.S. Department of Justice, returning in 1944. In 1948, he left Iowa to join the faculty at University of Pennsylvania Law School, where he taught for the rest of his career. His work focused on wills, estates, and future interests. He died in 1969.