When can a Fourth Amendment claim be dismissed on the merits of the federal district court?

When a Fourth Amendment claim is clearly defective in a manner not curable by amendment, however, the district court may dispose of it on the merits in the interest of judicial economy. Cf. Granberry v. Greer, 481 U.S. 129, 135, 107 S.Ct. 1671, 1675, 95 L.Ed.2d 119 (1987) (when claim is clearly without merit, federal court may dispose of habeas claim that has not been exhausted in state court). Here, the district court held that Trimble's Fourth Amendment claims were barred by the statute of limitations, and we affirm on that ground.