One of the interesting things about analogy-centric reasoning, prevalentin the Law, is that it actually makes slippery slope arguments pretty legitimate. If you decide to move the law in a given direction, you make it easier for the next lawyer to move the law a bit further, because you did X in Roe v. Doe, and X really isn't that different from Y, just a bit further along. And, of course, Y is quite similar to Z, and so on.
To illustrate: Why don't we allow children to vote? I don't mean, like, "lower the voting age to 16." I mean, "eliminate age as a requirement to vote at all." Let five year olds vote, if they want.
Why not? A few reasons that are oft proffered:
1. They're too dumb (can't properly consider the issues). We rejected this argument for denying the vote when we banned literacy tests.
2. They don't take voting seriously. Nor do a lot of Americans, but we don't require a seriousness test, and if we did it probably wouldn't pass Constitutional muster. Moreover, you certainly couldn't make the argument to blanket deny the franchise to an entire group as we currently do to children.
3. They're physically incapable of voting (applies to the very young kids). Lots of people with disabilities can't physically vote; we have provisions to assist them.
4. Their interests are already adequately represented by their parents. First, nonsense. Kids think very different things than their parents, and there's no reason to think their parents' interest entirely conform to theirs. Moreover, this argument was used to deny women the vote (their husbands could represent their interests) and was rejected. A further point: Each parent only gets one vote, but that one vote is supposed to represent the interest of one or more children. So a family of five with three non-voting-age children gets two votes. This argument fails basic tests of numeracy.
5. They're unduly influenced by their parents. This is the reverse of the last argument; they lack the basic autonomy required of a voter, they won't understand that they don't have to vote the way their parents tell them to, and they'll basically just serve as political dopplegängers of their parents. This is probably the most persuasive argument, because there aren't many analagous situations of one class having such immense psychological and intellectual control over another class.
6. Lack of physical interest in society (Lack of property). We don't truck with no poll taxes in America.
My essential point is that over the last century we've invalidated pretty much every argument that some group, for objective reasons, ought to be denied the franchise. This is a good thing, but it makes it much more difficult to justify denying the vote to remaining disfranchised populations out there. About the only remaining objective reason for disfranchisement that we accept, and it is controversial, is being guilty of a felony, which doesn't apply to children.
This is one of the troublesome things about the analogic reasoning of the law. Here, it's relatively benign; there's probably no problem with allowing children to vote. But it means that, when making a decision, a judge has to consider the possible implications of that decision down the line. Analogic reasoning makes law both more radical than it should be (taking a decision to its logical conclusion when society would perhaps not tolerate it) and more conservative than it should be (judges who might be inclined to move the law away from where it has been will hold back for fear that future judges will take the move too far).
So: Yeah.
