In many liberal democracies, particularly those that follow the parliamentary system of government, the elected members of a legislature who belong to a political party are usually required by that party to vote in accordance with the party line on significant legislation, on pain of censure or expulsion from the party. Sometimes a particular party member known as the whip is responsible for maintaining this party discipline. However, in the case of a conscience vote, a party declines to dictate an official party line to follow, and members may vote as they please. In countries where party discipline is less important, and voting against one's party is more common, conscience votes are generally less important.
Conscience votes are usually quite rare (except in certain countries, such as the United States, where they are the norm; see below) and are often about an issue which is very contentious, or a matter on which the members of any single party differ in their opinions, thus making it difficult for parties to formulate official policies . Usually, a conscience vote will be about religious, moral or ethical issues rather than about administrative or financial ones; matters such as the prohibition of alcohol, homosexual law reform and the legality of prostitution are often subject to conscience votes. In the British House of Commons there used to be a free vote (this, rather than "conscience vote", is the usual term in Britain) every few years on the restoration of the death penalty, abolished in 1964 (except for treason, for which it was finally abolished in 1998 in the Human Rights Act), which was always rejected; this practice has now been abandoned. In Britain, laws concerning abortion have always been subject to a free vote.
The proposed bans on hunting with dogs proposed by Tony Blair's government were the subject of several free votes in Parliament from 2001; on each occasion the Commons voted for a ban and the House of Lords rejected it. In 2004 the government, trying to placate the Lords and other opponents of a ban, proposed only restriction and licensing of hunting, but anti-hunting MPs (mostly Labour backbenchers) forced through an amendment which would effect a total ban; seconds after the (also free) vote on the amendment, Alun Michael and the government finally bowed to pressure and agreed to force the ban through the Lords under the Parliament Act. It passed in November 2004.
Other decisions which were taken by a free vote include abandoning the experiment with permanent summer time and bringing television cameras into Parliament.
Sometimes a vote may be free for some parties but not for others. For instance, when the Conservative government of Canadian Prime Minister Stephen Harper proposed a motion to re-open the debate on Canada's same-sex marriage laws, his Conservatives and the opposition Liberals declared it a free vote for their members, while the Bloc Québécois and the New Democrats both maintained party discipline to defeat the measure.
In the United States, parties exercise comparatively little control over the votes of individual legislators, who are almost always free to vote as they wish. Accordingly, most legislative votes in the United States can be considered free votes, although in rare circumstances a legislator may be disciplined by his or her party for a renegade vote; such discipline usually occurs only on votes regarding procedural matters on which party unity is expected as a matter of course, rather than substantive matters (for example, Democrat James Traficant was stripped of his seniority and committee assignments in 2001 when he voted for a Republican, Dennis Hastert, to be Speaker of the United States House of Representatives). Because free votes are the norm in the United States, the terms "free vote" and "conscience vote" are generally unused and unknown in that country.