FWIW, here's what the German constitution currently says about this:
Basic Law for the Federal Republic of Germany (Grundgesetz, GG)
Article 115 [Borrowing] (1) The borrowing of funds and the assumption of surety obligations, guarantees, or other commitments that may lead to expenditures in future fiscal years shall require authorization by a federal law specifying or permitting computation of the amounts involved. Revenue obtained by borrowing shall not exceed the total of investment expenditures provided for in the budget; exceptions shall be permissible only to avert a disturbance of the overall economic equilibrium. Details shall be regulated by a federal law.
(1) The borrowing of funds and the assumption of surety obligations, guarantees, or other commitments that may lead to expenditures in future fiscal years shall require authorization by a federal law specifying or permitting computation of the amounts involved. Revenue obtained by borrowing shall not exceed the total of investment expenditures provided for in the budget; exceptions shall be permissible only to avert a disturbance of the overall economic equilibrium. Details shall be regulated by a federal law.
But I guess this is too reasonable... The fact is that what we're experiencing right now is a top-down disaster. -Paul Krugman
The big parties changed that in the first Great Coalition government (1966-69) to their liking and benefit. Of course, it was okay to permit Keynesian fiscal policies, but the new rule permitted much more spending than justifiable.
In fact the legal investment category has been conceived by lawyers and does not make economic sense.
