Completing a doctorate in 1941, Prenner opened a law practice and earned a reputation for defending political prisoners and those accused of crimes against the state.

Now living as a male, his combative manner in the courtroom and strong sense of judicial independence led to his being imprisoned several times by the communist regime.

He was asked in 1968 to give the speech for the Bar Association's centennial celebrations and in 1970 was appointed as the permanent German-language court interpreter for Slovenia.

Changes in social conventions and celebrations for the hundredth anniversary of his birth have led to a re-examination of his life in biographies and documentaries, as well as publication of some of his previously unpublished autobiographical novels.

[3] He discarded his baptismal name and adopted the name Ljuba, a name with varied forms used for both males and females in various Slavic languages, as soon as he recognized his ability to think independently.

[10] He had a younger sister, Josipina, and an older half-brother, Ivan Čerče, an illegitimate child conceived before his mother married.

[14] Women created organizations and demanded equality in the new country, including the right to vote, earn a living, and access to education.

[17] In 1919, Prenner enrolled in the private Ptuj State Gymnasium and was able to finish three years before a lack of funds forced him to return home.

He studied his fourth year courses privately in Celje and then returned to Ptuj to take the examination to certify completion of the grade.

[5] He also began attending theater events and literary evenings that exposed him to Slovenian culture and instilled a desire to continue his education.

[3][19] In 1930, he successfully passed the Matura matriculation at the Ljubljana Lyceum,[20] having proven proficiency in English, French, German, and Italian.

[20] Between 1936 and 1937, he completed his legal internship with Josip Lavrič in Slovenj Gradec and then moved to Ljubljana to facilitate studying for a doctorate.

His short stories like Trojica (1929) and Življenje za hrbtom (1936), and novels such as Pohorska vigred v časopisu Jutro (1930–31) and Mejniki ali kronika malega sveta v reviji Ženski svet (1936–38), eschewed the prevailing Socialist realism model then popular for literary works.

Rather than an ideologically driven text, Prenner's works were characterized by the human ability to adapt to life with faith, humor, and irony.

The fact that he was born in what was now the German-controlled half of Slovenia would have prevented the Italian authorities from granting him a license to practice in their territory, which included Ljubljana.

[3][27] Now increasingly living as a male, during his doctorate studies Prenner joined the Osvobodilna fronta (Liberation Front, OF), an anti-fascist civil resistance movement.

In one scheme, he filed false paperwork with the authorities claiming that the judgments of the Italian courts were invalid after Italy capitulated to the Allies.

In the aftermath of the trial, he and the prosecutor, whose weak case he had exposed, engaged in a physical altercation, which resulted in Prenner being fined by the disciplinary court.

It alleged that he undermined the reputation and authority of prosecutors, the court system, the State Security Administration, and the government by inappropriately belittling the performance of officials.

[3] Though Prenner's comedy Veliki mož (The Great Man) was successfully staged in 1943 at the Ljubljana Drama Theatre, in 1947 it was attacked by the literary censors and he was expelled from the Writers Association.

Though highly skilled, Prenner's combative nature in court resulted in him being brought before the Bar Association's disciplinary commission several more times in the 1960s.

[10][5] He also wrote a letter to a colleague explaining that his appearance made his life as a lawyer simpler; though he recognized that he was not a man, he was more comfortable having the freedom to be who he felt he was.

[10] Prenner made no efforts to hide his sexual orientation[6][12] and his father accepted his gender identity, though his mother did not approve.

[10][37] The Bučinek family, which included the actress Jerica Mrzel [sl], provided support for Prenner while he became a father figure for the girls.

[23] In 1967, Prenner's comedy, Gordijski vozel (Gordian Knot) aired on the Italian station Radio Trst A, but he was still unable to publish in Slovenia.

In 1976, without his having sought acceptance, the Slovene Writers' Association readmitted him to membership and granted him a small pension based on his literary contributions from 1929.

[28] In 2000, Prenner's biography was published by Nova Revija, drawing on interviews with acquaintances[5] and he was included in the 2007 publication Pozabljena polovica: portreti žensk 19. in 20. stoletja na Slovenskem (The Forgotten Half: Portraits of Women of the 19th and 20th Centuries in Slovenia).

The biography for Prenner was titled "The Female Attorney in Trousers" (Odvetnica v Hlačah) referred to "her dual-gender identity" and used feminine pronouns for its subject.