Constitutional powers and responsibilities are divided between the U.S. federal and state governments. The two levels of government also share concurrent powers. The states are also constrained by the Constitution.
Additionally, a Federal President together with the Federal Council can support the government in a "legislatory emergency state" to enable laws against the will of the Bundestag (Article 81 of the Basic Law). However, so far the Federal President has never had to use these "reserve powers". Head of government