James Morrison Harris holds a robust educational foundation, having attended private schools and Lafayette College. He pursued legal studies and was admitted to the bar in 1843 after a period of travel in Europe. Harris spent nearly a decade practicing law in Baltimore, where he also engaged in community activities, including founding the Mercantile Library Association of Baltimore. His professional expertise was further demonstrated through his legislative achievements in Congress, where he promoted appropriation bills for infrastructure projects and opposed secession. Harris's leadership capabilities are evidenced by his involvement in community organizations, such as the YMCA and the First Presbyterian Church.

James Morrison Harris's political career is marked by a blend of local advocacy and principled opposition to divisive issues. His legislative focus on infrastructure funding for Baltimore reveals a localized strategy aimed at regional economic uplift. Despite his earlier affiliations with the Whig Party and the American Party, Harris's firm opposition to secession indicates an ideological stance that transcends party lines. His refusal to seek renomination in 1860 underscores a calculated approach to political alignment, driven by principle rather than expediency.