The architects of Proposition 40—California’s proposed 5 percent tax on billionaire net worth—say they want to tame inequality. But in their rush to redistribute wealth, they risk undermining something more fundamental: the rule of law.
F.A. Hayek warned that the crusade for “social justice” inevitably collides with the rule of law. The design of Prop 40 proves this point. According to Hayek, laws should meet three basic criteria: they should be non-retroactive, predictable in their consequences, and general rather than tailored to particular people or circumstances. Prop 40 fails on all three.
First, laws should govern future conduct, not rewrite the consequences of past decisions. Individuals should know the rules before they act, not discover them afterward. A retroactive tax moves in precisely the opposite direction, and Prop 40’s designers have already thrown that principle overboard.
Consider the timeline. The 2026 Billionaire Tax Act was filed on November 24, 2025. The initiative uses January 1, 2026, as the snapshot for tax residency in California and measures net worth as of December 31, 2026. Voters will not decide the measure until November 3, 2026.
In other words, who owes the tax was settled ten months before any voter marked a ballot. If approved, the law retroactively determines who qualifies as a taxpayer for wealth accumulated and decisions made before its passage.
Consider a billionaire who bought and sold assets, acquired real estate, donated to charity, restructured a business, or even moved to California under the assumption that no wealth tax existed. If the state later imposes a levy, those decisions cannot be undone. The ground rules were changed after the choices were already made.
Proponents defend the cutoff as a safeguard against capital flight, and argue that the measure was publicly filed in the fall of 2025. But a filed proposal is not a law. Initiatives can be rejected by voters or struck down by the courts. Hayek’s point is that people should be able to plan around laws, not speculate about what laws might eventually be enacted.
Once government begins attaching new legal obligations to circumstances that existed before those obligations were established, every taxpayer faces greater uncertainty about tomorrow’s rules. That leads directly to Hayek’s second principle: predictability.
The rule of law allows people to plan because they can reasonably anticipate how government will treat their actions: Families buy homes, businesses expand, entrepreneurs take risks, investors commit capital. All of these decisions depend, at least in part, on expectations about the legal environment.
When those expectations become uncertain, behavior changes. Billionaires may spend more resources protecting themselves against political and legal risk rather than creating businesses, hiring workers, or investing in California. And people naturally begin to ask: If the state can impose a tax based on circumstances that existed before the law took effect, what other legal expectations might be revised after the fact?
Hayek’s third principle is generality. Laws should establish general rules that apply equally, rather than function as instruments aimed at particular individuals or circumstances. Proposition 40 is difficult to square with that ideal. Its design is not incidental. It is built around a narrowly-defined class of extraordinarily wealthy taxpayers and a specific historical snapshot of their wealth and residency. The proponents know in advance whom the measure is intended to reach.
A government can, of course, impose taxes. The question is whether it does so through stable, prospective rules that citizens can anticipate and act upon, or through an imposition designed to capture a predetermined group based on circumstances that existed before the rules were established.
This distinction matters because legal stability is itself an economic asset. California has long presented itself as a global hub of innovation. But innovation depends on risk-taking, long-term investment, and forward-looking vision—activities that flourish when the rules of the game are known in advance.
Hayek reminded us that the road to serfdom does not necessarily arrive through sudden acts of coercion, it can emerge through gradual departures from the rule of law. Proposition 40 puts that principle to the test. If passed, it could establish a troubling precedent: that government can impose significant new obligations based on circumstances that existed before voters approved the law. California should think twice before taking that step.
