[16] In January 1928, E. E. Dudding, national president of the Prisoner's Aid Society, wrote to the Department of Justice nominating O'Toole to fill the vacancy on the bench of the District of Columbia Supreme Court caused by the resignation of Judge Adolph Hoehling, stating, "There is no better lawyer in Washington or anywhere else.

[18][19] Referring to O'Toole as a "pioneering woman member of the bench" and "a fixture in Washington's judiciary system", The Washington Post in 1934 reported on how, prior to her initial appointment, "the very mention of her name as a prospective member of the bench made usually dignified men pace the floor and use undignified language".

[11] In 1931, she was elected to the executive committee of the National Association of Women Lawyers,[20] which her colleague Dr Ellen Spencer Mussey had helped found in 1919.

[10][24][25] In September 1929, The Washington Daily News reported that O'Toole was "one of the most ardent anti-capital punishment workers in the District [of Columbia]".

That we constantly try to mitigate its horrors for ourselves by seeking and selecting the least painful methods of inflicting it, by limiting the number of witnesses, and so on, is the sure argument for its abolishment".

[26] O'Toole led a successful campaign to have the Washington Chamber of Commerce go on record as opposing capital punishment.

[26] An interview with O'Toole was published in The Washington Post on February 26, 1928, under the headline "High Divorce Rate a Sign of Progress: Some Very Frank Opinions From a Woman on the Bench, Judge Mary O'Toole, of the Municipal Court of the District of Columbia, and Why She Does Not 'View With Alarm' Recent Increase in Marriage Breaks".

On the club's ethos, O'Toole said the group hoped to attract not only women in the academic and professional sphere, but housewives as well.