Can a savings & loan sue the United States for breach of contract?

As an inducement for healthy savings and loans to take over ailing thrifts in “supervisory mergers,” federal regulators agreed to permit the healthy thrifts to apply an especially advantageous accounting method to their acquisitions during the savings and loan crisis of the 1980s. When Congress later passed legislation in response to the savings and loan problems, that law effectively disallowed the same method of accounting.
Three savings and loans that ran into trouble with the regulators successfully sued the United States for breach of contract, overcoming various defenses based on the sovereignty of the federal government. The decision means that the government may be exposed to billions of dollars in liability, not only to the savings and loans that sued, but also to over 100 other institutions that are in the same situation.