Maria was the daughter of the Mennonite preacher Allard Hulshoff (1734-1795) and Anna Debora van Oosterwijk (1745-1812), and for her whole life held onto her father's democratic, Patriotic and anti-Orangist views.
The strategy of her defenders Valckenaer and Willem Bilderdijk was not based on her birth, but was an apologia founded on the mental disturbance of a clergyman's daughter, stating that she was "in such a way touchingly thrown away from her naturally calm state of mind by her body" ("zodanig een aandoenlijk en door aandoenlijkheid buiten de natuurlijke staat van geestbedaardheid geworpen juffer").
During the trial Mietje suffered a nervous breakdown, which became apparent when, at the moment the judges ordered her to apologise, she suddenly could not produce a single word.
From 1811 until 1820 she lived as a voluntary exile in New York City in the United States, where she wrote and published in English her "Handbook for pacifist-republicans" under the title "Republicans' Peace Manual".
The subtitle of this work was borrowed from Propertius' Latin motto "In magnis volvisse satis" (or "sat est"), meaning "It is enough to have aimed for great things".
In her rooms at the Egelantiersgracht by the Lijnbaansgracht, on the upper storey of number 99, all that was found after her death was "an empty cabinet, a desk with some female clothes of little value, two boxes of books and writings, a rag-blanket, two old chairs, a bed with two cushions, a few further bits of undignified junk".
Contemporaries named her "geëxalteerd", "dweepzuchtig" or "hysterisch" ("hysterical"), since it was then considered that a woman should always hold her tongue on everything in the male-controlled domains of science, morals and politics.