Facts
The Federal Tribunal has been seized of several constitutional appeals against a Solothurn cantonal regulation regarding savings or prepayment contracts. This regulation provided, in particular, that the conclusion of such contracts was subject to official authorization, granted subject to compliance with various formal and substantive conditions. The Federal Tribunal ruled that this cantonal regulation encroached inadmissibly on the domain of federal civil law. In particular, the requirement of written form for the validity of the contract, the restrictions on prices and payment terms, as well as the provisions on termination and restitution of benefits were contrary to federal law. Only a few provisions, such as the prohibition of the exclusion of the constitutional court of jurisdiction, were deemed to be in conformity with federal law. Consequently, the Federal Tribunal annulled the cantonal regulation as a whole, as well as the decision of the Grand Council approving it, on the grounds that it violated the principle of the derogatory force of federal law.Considerations
According to the case law of the Federal Tribunal, the cantons may only enact public law provisions encroaching on federal civil law if this is justified by compelling public law reasons and if these provisions do not contradict the spirit and letter of federal civil law. In the present case, the Federal Tribunal acknowledged that there was a public interest in protecting buyers against the particular…