Today’s Supreme Court decision in Town of Greece changes, for the better, the use of a challenged practice’s history in interpreting the Establishment Clause.

In 2005, the Supreme Court on the same day held a display of the Ten Commandments on public property violated the Establishment Clause, while in another case, Van Orden, finding another such Ten Commandments perfectly constitutional. Obviously two such decisions are not easy to reconcile, and only one justice, Breyer, joined both opinions.

But one distinction is that the permitted display dated back to 1961, while the prohibited one was only erected in 1999. Justice Breyer made clear in a separate opinion that the longstanding presence of the former Ten Commandments was a major reason for their validity.

Thus the combination of the two Ten Commandments cases suggested a grandfather rule for religious displays. Those of a sufficient vintage would not be disturbed (perhaps since Lee v. Weisman?), while Moses-come-latelys were on notice that they would be taken down.

History matters in a very different way now. Town of Greece makes the relevant question the venerability of the general practice, not its particular challenged manifestation.

Today’s decision rejects the “grandfathering” model, at least as it was applied in Van Orden and McCreary. The legislative prayer in Town of Greece was an innovation dating only to 1999 – the same vintage as the McCreary Ten Commandments. Yet Justice Kennedy’s opinion sustaining it relied on the long history of legislative prayer in general, not the particular prayer in Greece. In the Ten Commandments context, this would make the question whether this kind of religious display has been around for a while, giving a presumption of validity to those that have. McCreary would have come out differently under this approach.

In effect, this inverts the grandfathering: anything of the kind historically allowed will continue to be allowed going forward (all things being equal), as opposed a rule that no more such things will be allowed.

The new approach makes more sense. A grandfathering policy implies the rules changed at some point, and that older displays will be tolerated merely for non-retroactivity type reasons. This raises the familiar Teaque question: if the new rule is so good, why not apply it across the board? And why is the Supreme Court innovating under color of the Establishment Clause?

The new approach to grandfathering starts with the assumption that it is not obvious what counts as an Establishment, but history and practice can help define it, as well as constraining the free hand of the Court.

Time for a new National Church?