After graduating from Harvard Law School and briefly practicing law with the firm of Vorys, Sater, Seymour and Pease, Smith joined the faculty at Capital University Law School in Columbus, Ohio in the fall of 1993. Smith's breakthrough came in 1996, when the Yale Law Journal published his article, "Faulty Assumptions and Undemocratic Consequences of Campaign Finance Reform."

In "Faulty Assumptions", Smith laid out a case against campaign finance regulation, arguing that efforts to regulate money in politics had been based on a series of incorrect beliefs about the effects of money in politics, and that as a result not only had "reform" failed to accomplish its objectives, it had made many of the problems worse. "Faulty Assumptions" contains no original research and little that is new in terms of Constitutional theory. Nevertheless, the article can be considered one of the most influential articles published on campaign finance in the last quarter of the twentieth century. The importance of "Faulty Assumptions" lay in its blending of existing political science research with legal and constitutional theory. Before "Faulty Assumptions", most legal scholarship on campaign finance had followed a narrative that assumed the corruptive and anti-egalitarian effects of large campaign contributions and spending, and had then focused on the creating a legal regime to control those effects and justify regulation against First Amendment claims recognized by the Supreme Court in Buckley v. Valeo. At the same time, these articles were largely ignorant of a growing literature in political science based on empirical studies of campaign spending and regulatory regimes. Smith's contribution was to bring these two arms of scholarship together, blending the growing body of empirical data to the constitutional and legal principles laid out elsewhere. The result was a devastating assault on the very foundation of campaign finance reform in both politics and constitutional law. Smith's analysis forced proponents of reform to rethink many basic assumptions, or at least to justify them against his critique.

Smith followed up the success of "Faulty Assumptions" with a series of academic articles further developing and refining his unique view, the most important of which is "Money Talks: Speech, Corruption, Equality and Campaign Finance", which appeared in the Georgetown Law Journal in 1997. "Money Talks" continues in the vein of "Faulty Assumptions" but with greater emphasis on Constitutional analysis.

Smith's work on campaign finance culminated in a book, Unfree Speech: The Folly of Campaign Finance Reform published by the Princeton University Press in 2001. Unfree Speech consists largely of updated and reworked versions of Smith's prior law review articles, along with some new material. By the time Unfree Speech was published, both Smith and his campaign finance scholarship had become something of a Rorschach test for attitudes about campaign finance. The book met with near universal praise among opponents of regulation, such as columnist George Will, who called it "the Year's most important book on governance," and condemnation from supporters of regulation, who lambasted it, in one reviewer's words, as "facile and boggling." Scholars such as the British political scientist Michael Pinto-Duschinsky were more balanced and generally complimentary, but by the time of publication Smith had been appointed to the Federal Election Commission and the book was largely reviewed as a political tract, rather than as the scholarly manuscript Smith presumably intended.

Nevertheless, Unfree Speech is an important academic work. It sold well enough to trigger the release of a paperback version in 2003. More importantly, Unfree Speech paved the way for later works. Before Unfree Speech, most books on campaign finance focused on sources of campaign funding and the creation of ideal regulatory regimes. Unfree Speech paved the way for a number of scholarly books more skeptical of campaign finance and its underlying assumptions, most notably John Samples' "The Fallacy of Campaign Finance Reform," but also including Rodney Smith's "Money, Power, and Elections," and less directly, works such as Melvin Urofsky's "Money and Free Speech" and Ray LaRaja's "Small Change." Compared to these later works, Smith's Unfree Speech is polemical and somewhat dated, but it remains a classic example of "anti-reform" literature, and is still assigned reading in many classes and seminars on campaign finance.

Smith's writings outside of the area of campaign finance reform have garnered far less attention, leading to criticism that he has been a "one-trick pony." Nevertheless, there is no denying his influence in both academic and popular debates on campaign finance reform.

Smith's ability to write for a general audience soon attracted the attention of politicians and think tanks in Washington. The libertarian Cato Institute published a Policy Analysis by Smith in 1996 (largely a slimmed down version of his Yale Law Journal article of the same title) which was widely distributed in Washington. Smith became a popular witness before congressional panels, both for his contrarian views and his ability to simplify complex issues for ease of consumption. The pro-reform Brennan Center for Justice would eventually refer to Smith as "the most sought after witness" to make the case against reform in Congress. Having gained the attention of Republican leaders in Congress, in 1999 then Senate Majority Leader Trent Lott, on the recommendation of Senator Mitch McConnell, sent Smith's name to the Clinton White House as the Republican choice to fill an upcoming Republican vacancy on the bipartisan Federal Election Commission, which oversees enforcement of campaign finance laws.

After a lengthy battle between Senate Republican leaders and the White House, Smith was nominated to a six year term on the FEC on February 9, 2000 by then-President Bill Clinton, and confirmed to the post by the United States Senate on May 24, 2000. By this time, Smith had established himself as one of the leading experts on campaign finance in the United States, with his writings on campaign finance and election issues having appeared in noted academic publications in addition to the Yale Law Journal, including the University of Pennsylvania Law Review and the Harvard Journal of Legislation. He had also been a regular witness before the United States House of Representatives and United States Senate on matters of campaign finance.

Because of his contrarian, deregulatory views on campaign finance, there was a strong objection to his nomination from reform advocates. The libertarian magazine Reason noted that virtually all reform advocates "agreed that he was the wrong person for the job". His nomination, however, received strong support from groups and organizations favoring deregulation of campaign finance, including, in addition to Reason, the Wall Street Journal, the Cato Institute, and others.

As Commissioner and later Chairman of the FEC, Smith remained controversial, particularly in 2004, when as Chairman he bucked the Republican Party and refused to support new regulations of so-called "527 groups," organizations largely unregulated by campaign finance laws that were generally believed to favor Democratic Presidential candidate John Kerry. Smith's tenure was otherwise marked by efforts to reform the FEC's enforcement proceedings to provide greater due process rights for respondents, and a staunch stand against expansion of the law into uncharted areas. Smith also supported the creation of an Administrative Fines program and an Alternative Dispute Resolution Office at the FEC. As Commissioner, he maintained an active speaking schedule and rarely toned down his criticism of the laws he was charged with enforcing. He resigned from the FEC in August 2005 to return to teaching, writing in his resignation letter to President Bush that, "Political activity is more heavily regulated than at any time in our nation's history."

After leaving the FEC, Smith returned to teaching at Capital University, and founded a non-profit organization, the Center for Competitive Politics, to promote deregulation of campaign finance. Smith is also a Senior Fellow at the Goldwater Institute, a member of the Board of Scholars at the Mackinac Center for Public Policy, and a member of the Board of Trustees of the Buckeye Institute for Public Policy Solutions. He serves on the Advisory Board of the Institute for Law and Politics at the University of Minnesota Law School, and on the Editorial Advisory Board of the Election Law Journal. In 2007-08, he was a member of Advisory Panel on the Constitution and the Courts for the presidential campaign of (Mitt) Romney. Gop3.com: The Triumvirate » Blog Archive » Romney Gets Big Shot Lawyers In May 2010 he was announced as one of four winners of the year's Bradley Prize, awarded annually by the Bradley Foundation to innovative conservative thinkers.

Smith, a Roman Catholic, lives in Granville, Ohio with his wife. He has two adult daughters.