One of the first things law students learn is that law is mostly about drawing lines between acceptable and unacceptable conduct. Some lines are easy to draw: murder is out; giving money to charitable causes is in. But even in these cases, there are definitional and moral puzzles at the boundaries. When is taking a life acceptable? Killing in war or self defense is generally OK, but what about unborn babies? What should count as a charitable cause? Giving to a church that runs a soup kitchen is OK, but it is difficult to imagine giving tax-favorable status to a mosque that raises money to pay for suicide bombers.
As can be seen from these examples, arguments about slippery slopes are closely related to line drawing problems. The typical slippery slope argument looks something like this: if we allow X, then inevitably Y will be permitted, where X is acceptable but Y is unacceptable. Lawyers deploy slippery slope arguments routinely, but we have reason to be cautious of them given their power. Sort of like invoking Hitler in a debate, they often prove too much.
So when we hear arguments that the government should not be permitted to eavesdrop on certain cell phone calls of suspected terrorists because inevitably such powers will be used to punish political enemies for what they say to their lovers, we should be skeptical. Perhaps the cynicism provides an important political check on misuse of power, but slippery slope argument can easily lead to nonsensical policy choices.
Consider this example ripped from today’s headlines. According to this story, a woman in Virginia suffocated her child to death, but cannot be charged with any crime because the baby was still attached by the umbilical cord. Why such a strange result? According to three legislators in Virginia who were asked to support a change in the law, the conduct is too close to legal abortion, and therefore might lead to criminal charges against doctors or mothers in those cases.
The slippery slope argument deployed here by these legislators is preposterous. Even accepting that abortion is legal in the third trimester (an almost unthinkable result), is it really the case that we cannot draw lines between a doctor and a woman deciding it is in the best interests of the lives involved to kill a new-born or nearly-born baby for medical reasons and a healthy mother smothering to death a healthy child in cold blood? There is no slippery slope here.
These bad arguments are not limited to particular ideologies. Gun-rights advocates routinely oppose restrictions on ownership, like licensing, education, and safety restrictions, out of fear that these regulations will inevitably lead to confiscation. Those who fear such a result have reason to deploy these arguments, but the rest of us have reason to oppose them when they are so outlandish. If the only thing preventing our government from seizing our weapons (or radios or whatever) is the absence of laws like these, then our society is in very bad shape indeed.
Of course, politicians deploy slippery slope arguments frequently because they use slippery slopes to their advantage. Incremental changes are often explicitly designed to wear down resistance to bigger changes that are planned for the future. The passage of SCHIP, a welfare program for health care for children (“It is for the children!”), is a good example. The plan was to start offering government-sponsored health care for the most sympathetic, and then, after achieving acceptance, move to other groups, such as the nearly poor, before finally offering government care for everyone. This is not as bad as it seems at first blush. If incrementalism can be used to provide information about or show the effectiveness of certain policies, then the approach is a sensible one. After all, if the people are strongly opposed to the new program, extensions will be unlikely.
In any event, there is nothing about the experience with SCHIP that says much about the woman in Virginia. She is a monster of the worst kind, and deserves to spend the rest of her years sleeping on a government matress behind government iron bars. The fact that we as a society are so polarized about abortion that the factions are pushed to such extremes (the other being the cold-blooded murder of doctors performing abortions) shows an absolute failure of the Supreme Court-centered approach to this issue. Slippery slope arguments in these cases are simply additional evidence of this failure.