Armed with detailed knowledge of Law 5.098, which specified numerous requisites for the right to vote while remaining moot on a woman's right to do so, Lanteri persuaded the precinct chair to accept her vote in the July 16, 1911, elections for the Deliberative Council, thus becoming the first woman to vote in South America; women were not granted the right to vote in Argentina nationwide until 1947. Electoral Law was amended that year to require military service (something required of all male Argentine citizens) in order to vote, again eliminating women. Lanteri instead joined her lawyer, Angelica Barreda, in forming a political party, the National Feminist Union, in 1918, and she ran for a seat in the Argentine Chamber of Deputies in every election thereafter until the 1930 military coup.