Sharpstein was born on May 3 or May 23, 1823 in Richmond, New York. In 1847, he moved to Sheboygan County, Wisconsin. Sharpstein was a member of the WisconsinState Senate from 1852 to 1853, representing the 16th district in 1852 and the 8th district in 1853. He was a member of the Wisconsin State Assembly in 1863. Previously, he had been District Attorney of Sheboygan County and of Kenosha County, Wisconsin. From 1853 to 1857, he was U.S Attorney of Wisconsin. In 1854, he represented the government in the fugitive slave cases, Ableman v. Booth and United States v. Booth, appealing up to the Supreme Court of the United States, where Chief Justice Roger Taney wrote the unanimous opinion. In April 1857, Sharpstein became Postmaster of Milwaukee, Wisconsin, and then was a delegate to the 1860 Democratic National Convention. In 1864, Sharpstein moved to California, was admitted to the bar in January 1865, and practiced law. In 1872, he published a book on insurance law. In January 1874, Governor Newton Booth appointed Sharpstein a judge of the Twelfth District Court in California, replacing Elisha W. McKinstry. In October 1875, he ran for election on the Republican ticket but lost the election to the district court to William E. Daingerfield. In July 1878, Sharpstein was nominated by the Workingmen's Party and elected as a member of the Constitutional Convention from the First Congressional District. In October 1879, when adoption of a new constitution required elections for all Supreme Court seats, Sharpstein was nominated by Democratic and Workingmen's parties and won a position as Associate Justice. When the term began January 5, 1880, the justices drew lots to determine their length of term, and he and Erskine M. Ross both drew three-year terms. In November 1882, both Ross and Sharpstein were re-elected on the Democratic ticket to 12-year terms. Among Sharpstein's notable opinions is Tape v. Hurley, 66 Cal. 473, holding the City of San Francisco excluding a Chinese child from public school violated the California Constitution. In July 1886, former Chief Justice David S. Terry filed a petition which unsuccessfully sought the removal of both Chief Justice Robert F. Morrison and Sharpstein on the basis of incompetence due to age. Sharpstein remained a member of the court until his death on December 28, 1892.
On November 17, 1845, Sharpstein married Catherine C. Crittenden in Macomb, Michigan. They had two daughters, who both died young in Michigan, and two sons, Jay Pitt Sharpstein, who lived in Berkeley, and William Crittenden Sharpstein, who graduated from Hastings College of Law and became an attorney.
