From 1945-1947 he served in the United States Army as a paratrooper and a criminal investigator; then earned his Bachelor of Science degree at St. Norbert College, and LL.B.

In 1956 he was elected to the 6th Senatorial District (the 7th, 10th, & 13th Wards of the City of Milwaukee) to succeed fellow Democrat William A. Schmidt, who was not running for re-election.

Moser obtained a plurality in a four-way Democratic primary election against State Representative Cecil B.

He easily turned aside challenges from Schaller in the 1960 primary, and from Republican Delbert Fowler in the general election; and served again as the Democratic floor leader in the 1961 session, leading the fight against the adoption of a sales tax in Wisconsin;[2] but resigned effective Feb. 1, 1962 to become a Milwaukee County judge.

[4] He was re-elected in 1977, and in April 1978 was elected to the newly created Court of Appeals District 1.