Finding no barriers to her admission, Langstaff enrolled at McGill University in 1911, graduating three years later as a Bachelor of Civil Law.

In 1915 she filed an appeal with the Court of King's Bench, which also ruled against her, claiming that her recourse was to petition the legislature, since they had enacted the statute defining who could become a lawyer.

The next year, joined by Leona Bell and Elizabeth C. Monk, Langstaff pleaded with the Quebec Bar Association to support their right to practice.

Frederick P. Walton, dean of the faculty, responded that no woman had ever asked for admission before, and while he was unsure of whether his colleagues would approve, she ought to begin attending lectures.

[17] The preliminary examination was open to male students before they began their studies, but anticipating that she might encounter difficulty, Langstaff had not applied until after she had already received her degree.

[5] A good deal of the court proceedings focused on the fact that Langstaff was raising her daughter as a single mother and did not know the whereabouts of her husband.

[17] After Saint-Pierre's comments had been widely publicized in newspapers throughout the United States and Canada, the issue became a cause célèbre for those involved in the struggle for women's suffrage.

[6][17] Langstaff was invited regularly to speak at suffragist rallies, where she stressed that equal opportunity was her goal[17] and filed an appeal with the Court of King's Bench.

[6][18] At the September 1915 hearing, the court's focus was again turned to the facts that she was not living with her husband, that he had not agreed to her attending law school, and that she was raising her daughter without his support.

[6][19][20] The basis of the ruling was that the intent of the law in Quebec was to exclude women from the legal profession because hearing cases which involved crimes of a sexual nature or obscenities "would bring into contempt her honor as a spouse or as a mother and to revile herself in the eyes of her husband, her children, and the male sex generally".

[15] Langstaff began to plan for introducing an amendment to the Bar Act at the next legislative session of the National Assembly of Quebec,[23] which would convene on 12 January 1916.

[25] Jacobs, using arguments supporting Langstaff's application written by Justice Lavergne, spoke to the committee along with feminists Grace Ritchie England and Marie Lacoste Gérin-Lajoie.

[26] Becoming the assistant to the other senior partner, Senator Lazarus Phillips,[25] Langstaff served as his secretary, a bookkeeper for the firm, and as a paralegal.

The debate clarified that the bar no longer objected to the admission of women and would allow a judge to grant her permission in the absence of a spouse.

[40] In 1939, she was one of the featured aviators in an air show held in Montreal in honor of King George VI and heir presumptive, Elizabeth.

[11] After having 13 suffrage bills defeated between 1922 and 1939, Quebec's feminists worked that year to convince Premier Adélard Godbout to keep his campaign promise to reintroduce the measure.

[21] On 29 April 1941, the legislature passed the bill[34] and in early 1942, Monk, Constance G. Short, and Marcelle Hemond were the first women admitted to the bar.

[25] As by that time, her daughter, who had become a nun in the Sisters of Holy Cross,[11][25] had already died, the medal was accepted by Davies Ward Phillips & Vineberg, the successor firm to her former employer.