Do state politicians have principles? To some cynical academics and activists, the only way this question can have an affirmative answer is to define the term the way comedian Groucho Marx famously did: “Those are my principles, and if you don’t like them … well, I have others.”

But for anyone who has watched politicians do their jobs up close and personal, it’s hard not to conclude that most of them spend most of their political careers advancing what they perceive to be principled positions on public policy. They don’t put their votes up for sale to the highest bid from potential donors.

Money flows from interested parties to politicians, of course — and this is true across the political spectrum. Labor unions and hardline environmentalists tend to contribute to liberals and Democrats. Business owners and hardline abortion foes tend to contribute to conservatives and Republicans.

In the vast majority of cases, however, politicians don’t change their views to get cash. The causal arrow points in the opposite direction. Incumbents express their general political philosophies in the form of votes. Candidates express them in the form of speeches or pledges. Private individuals and associations then choose the politicians whose views are closest to their own, and try to elect or re-elect them.

I said “in the vast majority of cases” instead of “in all cases” because there are, in fact, some exceptions to the rule. I’ve seen a few myself over the years, cases in which donors seemed to get not only special access to politicians but even acquiescence on legislation. Typically, these cases don’t involve ideological issues of longstanding dispute. Rather, they involve special budget provisions or narrow bills that give one special-interest group a leg up on another.

I’m all in favor of combatting such abuses. One effective weapon is maximum transparency. Budgets, supporting documents, and other public records should be instantly online and easily searchable. Committee meetings should be fully open, dutifully recorded, and held with due notice (and regularity). Political campaigns should be required to use software for booking donations that allows immediate public disclosure, not just eventual paper filings.

To say that private, voluntary funding of campaigns is inherently and systematically corrupt, however, is to go beyond reasonable precautions and a fair-minded reading of the data. It is a set-up. It is a ploy designed to pave the way for coercive limitations on political liberty — on the freedom of individuals to band together to say, print, or broadcast whatever they want, both during electoral campaigns and during political debates on local, state, and national issues.

A recent study of state lawmakers confirms my observations and those of other longtime analysts: most legislative outcomes are not related to the source of campaign contributions. In a paper published earlier this year by Legislative Studies Quarterly, political scientists Jeffrey J. Harden of the University of Colorado-Boulder and Justin H. Kirkland of the University of Houston looked at a “natural experiment” in New Jersey, where some lawmakers were allowed access to government financing for their campaigns while others were not, as well cases in Maine and Arizona where larger-scale systems of government financing were implemented.

Contrary to the usual assertions about money in state politics, Harden and Kirkland found that “public financing exerts a negligible effect on legislative voting behavior.” Legislators with publicly funded campaigns vote virtually the same way as legislators with privately funded ones. These findings appear to comport with those of previous studies on the same topic.

Again, this doesn’t mean we should disregard the risks of vote-buying or other forms of corruption. They do happen. But they are not the norm, and very real risks arise from an overreaction to low-probability events. Restrictions on freedoms of speech, press, petition, and association do tremendous damage to republican government and individual liberty. Make no mistake: many “campaign reformers” know that their favored schemes are feasible only after rewriting the First Amendment, either directly or through judicial activism.

That’s not an outcome worth buying at any price.

John Locke Foundation chairman John Hood is the author of Catalyst: Jim Martin and the Rise of North Carolina Republicans.