Augustinas Janulaitis (1878–1950) was a Lithuanian attorney, judge, and university professor who specialized in the legal history of Lithuania.

[3] His siblings included Catholic priest Pranciškus Janulaitis [lt], ophthalmologist Veronika Alseikienė, and dentist Julija Biliūnienė.

He participated in a campaign organized by Lithuanian periodicals Varpas and Ūkininkas to get the press ban lifted.

[1] Vaclovas Biržiška, at the time a student at the Šiauliai Gymnasium, later credited Janulaitis as the person who introduced him to Lithuanian publications.

[3] In August 1899, he played the role of Antanas in America in the Bathhouse in Palanga – the first Lithuanian-language theater performance in present-day Lithuania.

Janulaitis was arrested in 1900 when the police found an anti-Tsarist brochure and a list of Lithuanian books in his apartment.

[8] In February 1902, he was sentenced to three years of exile to Siberia, but he managed to escape to East Prussia, then to Scotland and Switzerland where he continued to study law at the University of Bern until 1905.

[8] From May 1902 to the end of 1905, Janulaitis edited Darbininkų balsas, the newspaper of the Social Democratic Party printed by Martynas Jankus.

[9] Janulaitis became the first to translate into Lithuanian The Communist Manifesto by Karl Marx and Friedrich Engels (published by Jankus in 1904).

Together with Mykolas Biržiška, he briefly edited Žarija [lt], a periodical of the Social Democratic Party of Lithuania.

[1] He worked as editorial staff of Darbo balsas [lt][21] and taught at the Lithuanian Gymnasium in Vilnius.

[1] In May 1918, Janulaitis, as a member of this commission, presented the council with a historical overview of courts in Lithuania and particularly of the medieval Lithuanian Tribunal.

[26] Janulaitis was appointed as chairman of the Vilnius District Court, but could not start the work due to the Lithuanian–Soviet War.

[27] He was briefly arrested by the authorities of the newly proclaimed Lithuanian Soviet Socialist Republic in January 1919.

He was the second judge to join the court and was its acting chairman until Antanas Kriščiukaitis arrived to Kaunas in June 1919.

[48] Despite this, the new Soviet regime demoted Janulaitis (Vaclovas Biržiška replaced him as the dean of the Law Faculty).

[52] The Soviets criticized Janulaitis for "twisting the history of Lithuania" and "inciting prejudice among the students against the Russian nation.

"[53] In 1947, Antanas Sniečkus, the First Secretary of the Lithuanian Communist Party, accused Janulaitis of keeping an apolitical stance and avoiding expressing opinions on the current political situation.

Sniečkus indicated that Janulaitis had expressed his political opinions in the past and specifically pointed out to anti-communist Lietuva ir šiuolaikinė Rusija (Lithuania and Modern Russia) published in 1925.

[55] During the Soviet period, Janulaitis published just one short article about the historian Teodor Narbutt,[51] even though he continued working on studies of the legal history of Lithuania.

[56] According to his niece Meilė Lukšienė, Soviet authorities made a decision to arrest Janulaitis in early 1950.

[64][65] Janulaitis was a strong adherent to the historical method based on the careful and critical analysis of primary sources.

[66] Janulaitis often selected a narrow topic and attempted to review and utilize all available primary and secondary sources.

[67] The adoption of this rigorous method led Janulaitis to conflicts with romantic historians, most notably with Jonas Basanavičius.

Janulaitis published a brochure criticizing Basanavičius, Jonas Šliūpas, Vincas Pietaris and their theories about the origins of the Lithuanian nation (first edition in 1903, second in 1907).

These articles are significant since Janulaitis used archival documents of the Šiauliai Economy [lt] that were lost during World War I.

[24] In an attempt to provide Lithuanian theater with material, he translated a number of plays by Herman Heijermans, Nikolai Gogol, Arne Garborg, Ludwig Thoma, Henrik Ibsen, Adolf Nowaczyński [pl], Friedrich Schiller, but published only three plays by Ibsen and one by Nowaczyński.

[1] In 1967, his widow Elena Jurašaitytė donated his archives to the Wroblewski Library of the Lithuanian Academy of Sciences.

[51] The archive contains materials from Janulaitis' life, his manuscripts of published and unpublished studies, and a collection of various 16th–20th century documents.

[84] In 2018, the Wroblewski Library of the Lithuanian Academy of Sciences held a month-long exhibition about Janulaitis' life and work on the occasion of his 140th anniversary.