The term itself likely stems from the commonplace practice of subordinate employees or officials being deputized and given the authority to sign the name of their superior or employer. In situations where this superior official's signature may frequently be required for routine paperwork, a literal rubber stamp is used, with a likeness of their hand-written signature. This could also be utilized personally by the individual named on the stamp, to prevent hand fatigue and save time when a large number of documents need to be signed. In essence, the term is meant to convey an endorsement without careful thought or personal investment in the outcome, especially since it is usually expected as the stamper's duty to do so. In the situation where a dictator's legislature is a "rubber stamp," the orders they are meant to endorse are formalities they are expected to legitimize.
The metaphor can also be used as a verb, to rubber-stamp.
Among auditors and military personnel, the synonymous term "pencil whip" is common.
Israel's stamp of approval for Germany's Left Party? Foreign Ministry invites party leader, despite anti-Israel views within its ranks
Feb 24, 2008; BENJAMIN WEINTHAL, Jerusalem Post correspondent Jerusalem Post 02-24-2008 Headline: Israel's stamp of approval for Germany's Left...