Attitude-Altering Slippery Slopes: Just What Will People Infer from Past Decisions?

[This month, I’m serializing my 2003 Harvard Law Review article, The Mechanisms of the Slippery Slope.]

From Legislative Decisions.—So far, I have argued that a legal rule may change some people’s attitudes: People may apply the is-ought heuristic and conclude that if the rule exists, its underlying justifications are probably sound. And this conclusion may in turn lead people to accept other proposals that rest on these justifications.

Attitudes, however, are altered by the law’s justifications as they are perceived. Say people conclude that A‘s enactment means that A is probably good, and that another proposal B is probably also good if it is analogous to A. Whether B is seen as analogous to A turns on which particular justification people ascribe to A, and see as being legitimized by A‘s enactment.

Consider, for instance, the tax for the support of Christian ministers that Madison condemned in his Memorial and Remonstrance. Madison reasoned:

Who does not see that the same authority which can establish Christianity, in exclusion of all other Religions, may establish with the same ease any particular sect of Christians, in exclusion of all other Sects? that the same authority which can force a citizen to contribute three pence only of his property for the support of any one establishment, may force him to conform to any other establishment in all cases whatsoever?

People should therefore be wary, Madison argued, of power “strengthen[ing] itself by exercise, and entangl[ing] the question in precedents”—they should recognize “the consequences in the principle,” and “avoid[] the consequences by denying the principle.”

But Madison’s argument implicitly turned on the justification the public would infer from the law and accept as a “precedent” for the future. If the justification was, to borrow part of the statute’s preamble, that the government may properly coerce people to do anything regarding religion, so long as such coercion supposedly has a “tendency to correct the morals of men, restrain their vices, and preserve the peace of society,” then Madison’s fears would have been well-founded. But if the justification was, to borrow another part, that the government may properly require people to pay a modest tax that will be distributed without “distinctions of preeminence amongst the different societies or communities of Christians,” then his concerns would be less plausible.

Unfortunately, we often can’t anticipate with certainty which principle a statutory scheme will eventually be seen as endorsing. Sometimes, the debate about a statute will focus on one justifying principle, and for some time after the statute is enacted, that will probably be seen as the principle that the statute embodies. But as time passes, the debates may be forgotten, and only the law itself will endure; and then advocates for future laws B may cite law A as endorsing quite a different justification.

Consider the installation of cameras that photograph people who run red lights. If the policy’s existence will lead people to conclude that the policy is good, and will thus lead them to view analogous programs more favorably, what justification for the policy—and thus what analogy—will people accept?

Some people will infer the justification to be that “the government may properly enforce traffic laws using cameras that only photograph those who are actually violating the law” (J1). Others, though, may draw the broader justification that “the government may properly record all conduct in public places” (J2). Decision A (cameras aimed at catching red light runners) might thus increase the chances that decision B (cameras throughout the city aimed at preventing street crime), which J2 would justify, will be implemented. {This result would be especially likely if public opinion on B we