Unanimity

Unanimity is agreement by all people in a given situation. Groups may consider unanimous decisions as a sign of agreement, solidarity, and unity. Unanimity may be assumed explicitly after a unanimous vote or implicitly by a lack of objections. It does not necessarily mean uniformity and can sometimes be the opposite of majority in terms of outcomes.

Voting

Practice varies as to whether a vote can be considered unanimous if some voter abstains. In Robert's Rules of Order, a "unanimous vote" is not specifically defined, although an abstention is not counted as a vote regardless of the voting threshold. Also in this book, action could be taken by "unanimous consent", or "general consent", if there are no objections raised. However, unanimous consent may not necessarily be the same as a unanimous vote (see Unanimous consent#Not the same as unanimous vote). In either case, it does not take into account the members who were not present.

In contrast, a United Nations Security Council resolution is not considered "unanimous" if a member abstains. In the European Union, the Treaty of Amsterdam introduced the concept of "constructive abstention", where a member can abstain in a vote where unanimity is required without thereby blocking the success of the vote. This is intended to allow states to symbolically withhold support while not paralysing decision-making.