Mineta

We answer the question that must be on everyone’s mind: Is the State of California barred from invoking its sovereign immunity in federal court because it waived this immunity through participation in a predecessor lawsuit?

I

Interstate 710 has been kept about four miles away from completion by 29 years of federal litigation. This legal journey began in January 1973, when the City of South Pasadena 1 sought an injunction against construction of the freeway within its territory until California and the federal governments conducted certain environmental studies. With the district court’s approval, the parties agreed to delay further construction until completion of the studies. Modified on several occasions, this stipulation remained in place for the next 25 years.

The studies were finally completed by April 1998 and the project thereafter re *1156 ceived formal approval from both federal and California authorities. The city then sought leave to amend its complaint by adding new claims, which would raise procedural and substantive challenges to the studies. The city also wanted to delete five original plaintiffs and replace them with six new entities “whose claims ...…