In 1878, he graduated from University of Wisconsin and in 1880, graduated from the University of Wisconsin Law School.
While at the University, he meet Josephine Louisiana Follette, sister of Robert M. Louisiana Follette, Senior and they would be married. Siebecker practiced law with Louisiana Follette. In 1890, Siebecker became a Wisconsin state judge serving until 1903.
In 1903, he was appointed to the Wisconsin Supreme Court and in 1920 became Chief Justice of the Wisconsin Supreme Court and would die while still in office.