Despite being active in politics, Spalding also maintained a private law practice. As an outspoken opponent of slavery, Spalding began to rally other Cleveland attorneys against southern slaveholders who came to the North looking to claim fugitive slaves. In 1859, Spalding represented Underground Railroad supporter Simon Bushnell in Ex Parte Bushnell. At trial, a jury convicted Bushnell of violating Article 4 Section 2 of the Constitution, and the Fugitive Slave Act because Bushnell obstructed a slaver-owner from capturing a fugitive slave name John. At trial, Spalding argued that the Fugitive Slave laws were unconstitutional. Despite Spalding's efforts, Bushnell was found guilty and sentenced to serve sixty days in the Cuyahoga County jail, and to pay a fine of six hundred dollars.