In his concurrence in United States v. Jones, Justice Alito was not willing to define the 4th Amendment in terms of history, but instead was willing to look into the future:
This case requires us to apply the Fourth Amendment’s prohibition of unreasonable searches and seizures to a 21st-century surveillance technique, the use of a Global Po-sitioning System (GPS) device to monitor a vehicle’s move-ments for an extended period of time. Ironically, the Court has chosen to decide this case based on 18th-century tort law. By attaching a small GPS device 1 to the underside of the vehicle that respondent drove, the law enforcement officers in this case engaged in conduct that might have provided grounds in 1791 for a suit for trespass to chattels. 2 And for this reason, the Court concludes, the installation and use of the GPS device constituted a search. Ante, at 3–4.
This holding, in my judgment, is unwise. It strains the language of the Fourth Amendment; it has little if any support in current Fourth Amendment case law; and it is highly artificial.
…
The Court argues—and I agree—that “we must ‘assur[e] preservation of that degree of privacy against government that existed when the Fourth Amendment was adopted.’ ” Ante, at 5 (quoting Kyllo v. United States, 533 U. S. 27, 34 (2001)). But it is almost impossible to think of late- 18th-century situations that are analogous to what took place in this case. (Is it possible to imagine a case in which a constable secreted himself somewhere in a coach and remained there for a period of time in order to monitor the movements of the coach’s owner? 3 ) The Court’s theory seems to be that the concept of a search, as originally un-derstood, comprehended any technical trespass that led to the gathering of evidence, but we know that this is in-correct.
Yet in Perry, Alito was very concerned about the future effects of same-sex marriage.
The one thing that the parties in this case 20 seem to agree on is that marriage is very important. 21 It’s thought to be a fundamental building block of 22 society and its preservation essential for the 23 preservation of society. Traditional marriage has been 24 around for thousands of years. Same-sex marriage is 25 very new. I think it was first adopted in The 1 Netherlands in 2000. So there isn’t a lot of data about 2 its effect. And it may turn out to be a — a good 3 thing; it may turn out not to be a good thing, as the 4 supporters of Proposition 8 apparently believe. 5 But you want us to step in and render a 6 decision based on an assessment of the effects of this 7 institution which is newer than cell phones or the 8 Internet? I mean we — we are not — we do not have the 9 ability to see the future.
So you got that? GPS on cars? Doesn’t matter what history says, it’s bad. Same-sex marriage? Let’s wait and see.
Update: Solicitor General Verrilli addresses this point later, in a stab to Alito:
And the fourth point I would make, and I do think this is significant, is that the principal
argument in 1967 with respect to Loving and that the Commonwealth of Virginia advanced was: Well, the social science is still uncertain about how biracial children will fare in this world, and so you ought to apply rational basis scrutiny and wait. And I think the Court recognized that there is a cost to waiting and that that has got to be part of the equal protection calculus.
And so — so I do think that’s quite fundamental.
Update 2: Nelson Lund writes in WSJ that same-sex marriage supporters can’t back up claims of the positive long-term effects.
A significant number of organizations representing social and behavioral scientists have filed briefs promising the court that there is nothing to worry about. These assurances have no scientific foundation. Same-sex marriage is brand new, and child rearing by same-sex couples remains rare. Even if both phenomena were far more common, large amounts of data collected over decades would be required before any responsible researcher could make meaningful scientific estimates of the long-term effects of redefining marriage.
The conclusions in the research literature typically amount at best to claims that a particular study found “no evidence” of bad effects from child rearing by same-sex couples. One could just as easily say that there is no reliable evidence that such child-rearing practices are beneficial or harmless. And that is the conclusion that should be relevant to the court.