Born on January 9, 1899, in Meriden, New Haven County, Connecticut, Danaher attended the local schools.

He received an Artium Baccalaureus degree in 1920 from Yale University and then attended Yale Law School, serving as a lieutenant in the United States Army in 1918 as a member of the Student's Army Training Corps and in the Officers' Reserve Corps.

[1][2] Danaher received a recess appointment from President Dwight D. Eisenhower on October 1, 1953, to a seat on the United States Court of Appeals for the District of Columbia Circuit vacated by Judge James McPherson Proctor, taking the oath of office on November 20, 1953.

After taking senior status, he served part time with the United States Court of Appeals for the Second Circuit.

[1][2] Danher's grandson, John A. Danaher III, is a Superior Court Judge who currently sits in Litchfield, Connecticut.