Judge Spaeth took the Common Pleas bench in 1999, following service as Judge of Fairfield Municipal Court. He is the longest serving trial judge in Butler County.

In addition to his regular docket, Judge Spaeth has presided over Drug Court since 2000. Drug Court is a separate, specialized docket in which non-violent, drug-dependent offenders are provided intense, court-supervised treatment as a condition of probation.

He serves as a Conservancy Court Judge for the Miami Valley Conservancy District, a Board Member and Past President of the Ohio Justice Alliance for Community Corrections (OJACC), an Advisory Member of Miami Valley Health Services Board and is a Member and Past President of the Lindenwald Kiwanis Club. He previously served as an Advisory Member of the Ohio Sentencing Commission; board member of the American Heart Association, Drug Counseling Services, Fairfield Chamber of Commerce, Ohio Association of Drug Court Professionals and Union Township Chamber of Commerce; and president and board member of Butler County Alcohol and Drug Addiction Services Board. In 2017, Judge Spaeth was awarded the Southwest Ohio Trial Lawyers Association Trial Judge of the Year. In 2019 he was awarded the Representative C. J. McLin Award by OJACC for his contributions to the improvement of community corrections in Ohio.

Judge Spaeth attended Badin High School and went on to play football for, and graduate from, Purdue University in 1983. In 1986, he graduated from the University of Dayton Law School.

Prior to serving on the bench, Judge Spaeth was a partner with the law firm of Millikin and Fitton.