LA Times Supreme Court reporter David Savage notes a trend with the Roberts Court -- requiring proof of constitutional violations in practice, not in abstract.
Here's the basic concept: there are two ways to challenge the constitutionality of a statute. First, the "facial" challenge whereby the plaintiff claims that the law itself is unconstitutional simply because of what the ordinance/statute/regulation says. For example, if New York enacted a statute stating that the official religion of the state is Presbyterianism and the plaintiff challenged the law's content, that's a facial challenge. Of course, this is an extreme scenario because it entails a state legislature enacting a measure directly contrary to a Constitutional provision. Real cases are not so stark -- such as the Voter ID case the Court decided Monday.
The second type is the "as applied" challenge. In that scenario, the plaintiff claims that the law is unconstitutional as the government has applied it to the plaintiff's specific situation. For example, litigation by certain American Indian prisoners who have claimed that prison drug policies curtail their right to the Free Exercise of their religion because they cannot use peyote in specific religious rituals.
In the past three years, facial challenges have been unsuccessful with the Roberts Court. Thus, Savage notes that the Court has sent a message to litigants: "Produce evidence that a law has actually violated someone's rights, and name names if you can." And this is good because the Court reinforces the presumption that legislatures act legitimately when enacting broad laws.