[1] Leche was acting legal clerk (fiskal) in the Svea Court of Appeal in 1925, co-opted member (adjungerad ledamot) of it in 1926 and assessor in 1929.
He was a co-opted member of the Water Court of Appeals (Vattenöverdomstolen) in 1929, an assistance at the Ministry of Justice in 1932 and acting judge referee in 1933.
Leche push through the decision to establish the General Security Service with the help of Torsten Nothin and Olof Thörnell.
He was expert for law-making of the courthouse construction obligation (tingshusbyggnadsskyldigheten) and was chairman of the committee for the reorganization of the fortification police in Boden in 1941.
Leche was chairman of the committee for the investigation of the police officer's right to use force in 1942 and member of Procedural Board (Processnämnden) from 1946 to 1948.