First elected to the court in 1902, he became the youngest chief justice in the United States at the time.

He later attended Carson College in Jefferson City, leaving in his junior year.

When Senator Weldon Brinton Heyburn died in 1912, Ailshie ran unsuccessfully in 1913 for the seat, then filled by Kirtland I. Perky, but he lost the race to James H. Brady.

Ailshie resigned his seat on the Idaho Supreme Court in 1914, a few months before his term expired.

That year Ailshie moved to Coeur d'Alene, Idaho, and resumed his law practice.