rubber stamp

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A piece of rubber affixed to a handle and bearing raised characters used to make ink impressions, as of names or dates.
• noun A person or body that gives perfunctory approval or endorsement of a policy without assessing its merit.
• noun A perfunctory approval or endorsement.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective figuratively Of a person, organisation, or process, making decisions or approving matters routinely or without real power, as rubber stamp politics, a rubber stamp committee.
• noun A piece of rubber or similar material with a design or text carved or molded for the purpose of transferring ink or dye to imprint that design on another object.
• noun figuratively A person or organisation who approves, routinely or as a formality, matters decided by some other person or organisation.
• verb colloquial to process, approve or decide matters routinely rather than through careful consideration

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a stamp (usually made of rubber) for imprinting a mark or design by hand
• noun routine authorization of an action without questions