Rubber stamp, is a political metaphor referring to an institution that has little power and rarely disagrees with more powerful organs, though usually it formally has much greater power. For example, in a dictatorship, the parliament may be little more than a rubber stamp of approval on the dictator's decrees. Conversely, in a constitutional monarchy, the monarch is typically a rubber stamp to an elected parliament, even if he or she legally possesses considerable reserve powers and/or disagrees with the parliament's decisions.
Rubberstamp is also an artificial verb referring to the above mentioned adjective.
