Is a lache barred from raising Williamson County as a defense?

Finally, plaintiffs assert that defendants are barred by laches from raising Williamson County as a defense. ³ Defendants respond that laches cannot bar their Williamson County defense because the failure to seek compensation in state court renders the taking claim unripe, and lack of ripeness deprives the court of subject matter jurisdiction. See Austin v. City and County of Honolulu, 840 F.2d 678, 682 (9th Cir.1988). We agree with defendants that ripeness is a jurisdictional requirement and lack of subject matter jurisdiction may not be waived. ⁴