Born in Trenggalek, East Java, Soeprapto studied law in Jakarta, finding work in the legal system soon after graduating in 1920.

Escaping Pekalongan during Operation Product with the help of a prisoner he had just sentenced, Soeprapto made his way to Yogyakarta and began to work as a prosecutor.

For fifteen years he worked at Landraad in various locations, including in Surabaya, Semarang, Bandung, and Denpasar.

[1] While in Pekalongan, Soeprapto befriended a local prosecutor Soekarjo Kario Hatmodjo, father of Hoegeng.

[2] Although Soeprapto was able to lead the court peacefully during the Japanese occupation, after the start of the Indonesian National Revolution the situation in Pekalongan became unstable.

Although the nascent army was able to hold the peace during riots at the end of 1945, when the Dutch began a major assault on Java, Soeprapto was forced to flee south to Indonesian-held areas with his family.

He later began work as a prosecutor, rising quickly through the ranks; several of his coworkers attributed it to the Kutil case, where Soeprapto demonstrated that he believed in the supremacy of law.

Moeljatno took the traditional view that the prosecutor general's office, under the control of the Ministry of Justice during the Dutch colonial period, was in a similar station after independence; on the other hand, Soeprapto believed that the function of the prosecutor general was half executive and half judicial and as such demanded to be accountable only to the cabinet.

[8] the dismissal has been reported in several sources to be related to the acquittal of/dropping of charges against two foreigners, Junschlager and Schmidt, who had been accused of undermining the government; Junschlager died in prison, and Schmidt was freed based on time served in a high court decision which the prosecution did not appeal.

[8][10] As he had not been given prior warning he was unable to go to Merdeka Palace for the related formalities; at the time he was visiting his parents in Yogyakarta.