Slippery Slope June: An Introduction to Thinking About Slippery Slope Arguments

[This month, I’m serializing my 2003 Harvard Law Review article, The Mechanisms of the Slippery Slope; I’ll begin here with a slightly reordered introduction, which generally summarizes my analysis, but if you want more details, you’ll get them in later posts.]

Consider one classic slippery slope claim (more shortly on why it makes sense to so label it): the claim that gun registration (A) might lead to gun confiscation (B). (This was written before D.C. v. Heller (2008) held that gun confiscation is unconstitutional; but Heller, which is a 5-4 decision, may be seen as potentially vulnerable to overruling in the future, and in any event may leave room for confiscation of particular categories of weapons.) Setting aside whether we think this slippery slope is likely—and whether it might actually be desirable—it turns out that the slope might happen through many different mechanisms, or combinations of mechanisms:

1. Registration may change people’s attitudes about the propriety of confiscation, by making them view gun possession not as a right but as a privilege that the government grants and therefore may deny.
2. Registration may be seen as a small enough change that people will reasonably ignore it (“I’m too busy to worry about little things like this”), but when aggregated with a sequence of other small changes, registration might ultimately lead to confiscation or something close to it.
3. The enactment of registration requirements may create political momentum in favor of gun control supporters, thus making it easier for them to persuade legislators to enact confiscation.
4. People who don’t own guns are more likely than gun owners to support confiscation. If registration is onerous enough, over time it may discourage some people from buying guns, thus decreasing the fraction of the public that owns guns, decreasing the political power of the gun-owning voting bloc, and therefore increasing the likelihood that confiscation will become politically feasible.
5. Registration may lower the cost of confiscation—since the government would know which people’s houses to search if the residents don’t turn in their guns voluntarily—and thus make confiscation more appealing to some voters.
6. Registration may trigger the operation of another legal rule that makes confiscation easier and thus more cost-effective: if guns weren’t registered, confiscation would be largely unenforceable, since house-to-house searches to find guns would violate the Fourth Amendment; but if guns are registered some years before confiscation is enacted, the registration database might provide probable cause to search the houses of all registered gun owners.

In the registration-to-confiscation scenario, only the latter two mechanisms seem fairly plausible to me; in other scenarios, others may be more plausible. And there are of course mechanisms that may work in the opposite direction, so that decision A may under some political conditions make decision B less likely. (For instance, gun registration might energize gun-rights groups, and lead them to be even more effective in fighting broader gun controls; or if gun registration seems ineffective or unduly intrusive, some for