Shapiro v. McManus, 136 S. Ct. 450

In 2011 Maryland adopted a congressional redistricting plan; petitioners (bipartisan citizens) sued claiming the plan burdened their First Amendment right of political association.
Petitioners requested a three-judge district court under 28 U.S.C. §2284(a), which mandates convening a three-judge court for challenges to congressional apportionment.
The district judge concluded petitioners’ claim could not obtain relief (invoking Rule 12(b)(6) standards) and dismissed the complaint without notifying the circuit chief judge to convene a three-judge court.
The Fourth Circuit summarily affirmed the dismissal.
The Supreme Court granted certiorari to decide whether a district judge may refuse to convene a three-judge court by dismissing the case on the merits or as constitutionally insubstantial.

Issue	Plaintiff's Argument	Defendant's Argument	Held
Whether a district judge must refer a §2284(a) apportionment challenge to a three-judge court	Shapiro: §2284(a) is mandatory; the judge must initiate three-judge procedures when an apportionment challenge is filed	McManus: The §2284(b)(1) phrase “unless he determines that three judges are not required” permits a district judge to refuse referral (e.g., dismiss under Rule 12(b)(6))	Court: §2284(a) is mandatory; §2284(b)(1) limits the judge only to determining if the request fits §2284(a), not to resolve merits or refuse referral
Whether Goosby-style “constitutionally insubstantial” screening can justify denying a three-judge panel	Shapiro: Petitioners’ claim is not frivolous and invokes a recognized legal theory (Justice Kennedy’s Vieth concurrence)	McManus: District courts may dismiss insubstantial constitutional claims and so avoid convening three judges	Court: Only claims that are "wholly insubstantial, frivolous, or essentially fictitious" permit jurisdictional dismissal; petitioners’ theory clears that low bar, so referral was required

Lexecon Inc. v. Milberg Weiss Bershad Hynes & Lerach, 523 U.S. 26 (1998) ("shall" normally creates a nondiscretionary obligation)
Goosby v. Osser, 409 U.S. 512 (1973) (pre-1976 discussion of "constitutionally insubstantial" claims and three-judge requirement)
Bell v. Hood, 327 U.S. 678 (1946) (distinguishes jurisdictional insubstantiality from merits failure)
Vieth v. Jubelirer, 541 U.S. 267 (2004) (Kennedy concurrence proposing First Amendment-based standard for partisan gerrymandering)
Ashcroft v. Iqbal, 556 U.S. 662 (2009) (pleading standard cited by the district court)
Bell Atlantic Corp. v. Twombly, 550 U.S. 544 (2007) (pleading standard cited by the district court)
Washington v. Confederated Tribes of Colville Reservation, 447 U.S. 134 (1980) (constitutional claims not lightly deemed insubstantial)
Steel Co. v. Citizens for Better Environment, 523 U.S. 83 (1998) (frivolous or immaterial claims and jurisdictional principles)