Leib was born in Philadelphia, Pennsylvania to George and Dorothea Leib.[1] He studied and practiced medicine in Philadelphia, received a commission as a surgeon in the Philadelphia Militia in 1780 and served during the American Revolutionary War. Following the war, Leib returned to Philadelphia and continued the practice of medicine. He served on the staff of several Philadelphia hospitals and was a member of the committee of correspondence in 1793.[2]
He was one of the organizers of the German Republican Society in Philadelphia.[3] He represented the large German immigrant population in Philadelphia. He and Benjamin Bache became a part of a radical faction of the Society which led to a schism in the Society over the Whiskey Rebellion. Leib and his brother volunteered to join the military force sent to control the insurrection.[4]
From 1805 to 1809, a power struggle ensued in the Pennsylvania Republican Party with Leib and William J. Duane on one side and Simon Snyder on the other. Duane and Leib represented the interests of Philadelphia, such as banking, trade and shipping, whereas Snyder represented the interests of rural Pennsylvania such as land ownership.[5]
In 1807, he was elected Brigadier-General of the Second Brigade of the Philadelphia Militia.[6]
Leib was elected as a Democratic-Republican to the United States Senate by the state legislature in December 1808. Leib was elected to the term beginning on March 4, 1809, but assumed office on January 9, 1809, following the resignation of Samuel Maclay.[2]
In 1809, he was a member of the committee that formed the "Whig Society of Pennsylvania".[6]
He served as a U.S. Senator until February 14, 1814, and resigned to serve as postmaster of Philadelphia from 1814 to 1815.[7] He returned to the Pennsylvania House for a third time, from 1817 until 1818 and served as a Pennsylvania State Senator for the 1st district from 1818 until 1821. He became prothonotary of the United States district court in Philadelphia in November 1822 and served in that role until his death in December 1822.[8][9]
He was interred at St. John's Lutheran Churchyard in the Northern Liberties neighborhood of Philadelphia.[2] In 1924, he was reinterred to the Laurel Hill Cemetery in Philadelphia when the church and burial ground were demolished during the construction of the Benjamin Franklin Bridge.[10]
