Unanimous consent is an agreement by all members present on anything requiring a yes or no decision. If a family all agrees to have pizza for dinner, this can be considered unanimous consent to have pizza. However, in anyone objects to pizza, unanimous consent is not achieved, and the decision may have to come down to either a vote or parental discretion.

In Congress, unanimous consent is a way of quickly deciding issues without taking a vote. Issues where unanimous consent may be readily obtained are noncontroversial ones. So for example, by unanimous consent, a way to proceed in a hearing might be readily achieved.

If Congress wishes to table an issue and no one objects, this move can be considered as unanimous consent. Alternately, Congress might decide by unanimous consent to have Democrats and Republicans take turns arguing an issue. Though the issue itself may not have unanimous consent, the procedure for arguing the issue may.

At times, all members present in Congress approve bills or confirmation hearings without objection. When most of congress knows something will be approved with unanimous consent it is superfluous to take a vote. Generally a statement first calls for any objections to be raised. If no objections are raised, no vote is needed, so whatever decision needs to be made is adopted with unanimous consent.

Unanimous consent in Congress saves time for the debates and votes needed on issues likely to spark controversy. It helps that a bi-partisan Congress can agree on certain things in order to get on with the real debates.

Unanimous consent cannot be achieved if members of Congress object to it. So, for example, it is often unlikely that decisions like confirmations of Supreme Court Justices or amendments to the constitution will be made without a vote.

In rare situations, as after the 9/11 attack in the US, Congress adopted several measures by unanimous consent because much support existed for the president and for his party. However, several months after 9/11, party divisions began to reassert themselves, and issues once again became more likely to be voted on, than to be passed with unanimous consent.

One further distinction in unanimous consent in Congress needs to be made. Unanimous consent can only refer to the members of Congress that are present. A person, who objects to something but is not there to object, essentially has no vote, and is not considered in deciding unanimous consent.