Stallo, among with George Hoadly (later governor of Ohio) and Stanley Matthews (later an associate justice of the U.S. Supreme Court), served as the school board's counsel.

Stallo's arguments on appeal to the Ohio Supreme Course led to a unanimous reversal of the lower court and reinstatement of the ban on Bible-reading in 1872.

He was rewarded for his support of the Democratic candidate, Grover Cleveland, in 1884, by appointment as Ambassador (`Envoy Extraordinary and Minister Plenipotentiary') to Italy (1885–1889).

He declared that at a recent conference of statesmen and diplomatists, Judge Stallo had carried off all the honors—speaking with ease, as might be necessary, in Italian, French, and English, and finally drawing up a protocol in Latin.'

After Cleveland lost his first re-election campaign to Benjamin Harrison in 1888, Stallo retired to Florence, Italy and there assembled a collection of his essays written in German, Reden, Abhandlungen und Briefe.

A French translation [4] was issued in 1884, with a foreword by Charles Friedel[5] Archived 2007-03-12 at the Wayback Machine[6] Among many others, the second edition was read by Bertrand Russell[7], who awarded it three footnotes in his An Essay on the Foundations of Geometry (1897).

Die Begriffe und Theorien der Modernen Physik was published in 1901 (Barth, Leipzig) and re-issued in 1911 with a short new foreword by Kleinpeter.

In Ch XIV, "Metageometrical Space in the Light of Modern Analysis Riemann's Essay," Stallo flamingly critiques Riemann's "On the Hypotheses which lie at the Base of Geometry," ending with the statement that "the analytical argument in favor of the existence, or possibility, of transcendental space is another flagrant instance of the reification of concepts.