A per curiam opinion relating to redistricting which is probably why the Court did not wait until today to deliver it.
Tennant v. Jefferson County CommissionReversed the decision of the District Court for the Southern District of West Virginia and affirmed the validity of the U.S. Congressional redistricting plan adopted by West Virginia.
Basically reaffirmed
Karcher v. Daggett, 462 U. S. 725 (1983), but added the guidance that while computer technology makes it easier to devise districts that are mathematically equal in population than was the case then, that does not affect the validity of other legitimate state interests such as keeping political subdivisions intact, minimizing population transfer between districts, and determining whether incumbents will or will not have to face each other.
The plan West Virginia adopted has a population variance of 0.79%, second highest of the plans considered, but it was the only one that met the other interests the state had.
While the court did not explicitly say so, I think that plans with a variation of 1% or less can be considered generally safe from court challenge.