This is the form of debating that is used at the World Championships and is one of the commonest debating styles, and can be contrasted with the styles that the Americans use (I'm not familiar with that, so if someone is, please do node about it). Here are the rules of the game:

The format of the debate:

The debate consists of four teams of two people each (who are known as members), a chairperson known as the Speaker and an adjudicator, or more usually, a panel of adjudicators.

The teams consist of the following members:

Opening Government comprising the Prime Minister or the First Government member and the Deputy Prime Minister or the Second Government Member. They are then followed by the Opening Opposition comprising the Leader of the Opposition or the First Opposition Member and the Deputy Leader of the Opposition] or the Second Opposition Member. Then you have the second teams (these are NOT second string teams and are not called 'second teams', but merely second in order, but they don't speak second...!): This includes Closing Government comprising the Third Government Member and the Government Whip and finally the Closing Opposition comprising the Member of the Opposition and the Opposition Whip.

The members speak in the following order:

Prime Minister
Opposition Leader
Deputy Prime Minister
Deputy Opposition Leader
Member for the Government
Member for the Opposition
Government Whip
Opposition Whip

The motion

This must be clearly worded and reflect the nature of the debate. Since the British parliamentary style is used by a number of countries, if you're having an internal regional debate then you might include a motion on current affairs relating to your region. But at the World Championships, the motion must reflect the international nature of the competition. The motion is the most crucial part of the debate. It is the duty of the First Government Member to define the motion clearly and lay out what the government considers the definition of the motion to be. Now you may ask, why are definitions so crucial? This is because both motions and definitions may not be obvious.

To give you a classic example. Let's take the motion This House believes in Smokers' Rights. Here, the word 'smokers' could defined as 'Third World Polluting countries. So the argument then hinges on pollution in the First World versus the Third, the Kyoto Protocol and so on. This is perfectly acceptable. You may modify a motion, within certain permissible limits to alter the contours of the debate.

Let's take a few more examples. Take the motion This House would Trade Land for Peace. As a member of the First Government in an international debate, you could debate this in terms of the general principles of giving up territory to secure both short and long term peace. However, you could restrict your debate to say the Middle East (the arguments for which all participants at the World Championships should be familiar with) but you CANNOT restrict it to say discussing Sri Lanka and the LTTE. You will then get challenged on the grounds that you have 'set place'. However, say this debate was taking place in India, you could restrict your defintion to discussing the Kashmir issue. No matter what your definition, as long as it's legal, the opposition MUST adhere to it.

Take one final look at controversial or 'open' motions. A common one is This House would Play God- this could be interpreted in a variety of ways- abortion, cloning, capital punishment and so on. But as long as the definition provided by the First Government member is clear, coherent and logical and allows sufficient ground for debate, there is no ground for the motion to be challenged.

However, only the Opening Government has the opportunity to define the motion and they are judged on their ability to do so. A poorly defined motion will not invite the wrath of the opponents but also lead to a deduction of marks.

What happens if you don't agree with the definition?

Then you challenge it! But you must be the Leader of the Opposition to challenge a definition and you can do so on the following grounds: the definition is self-proving (truistic or tautological); or
the definition has no clear and logical link to the motion; or
the definition has been squirreled; or
the definition has time or place set to the debate.

The onus is on the Opposition to prove that the definition as provided by the Proposition/Government was unreasonable. They must then provide an alternate defintion and the debate is then reduced to debating the two definitions rather than the issue at hand. If at the end of the debate, the judges concur with the Opposition's challenge, they win. But if the challenge is rejected, then they lose, even if they may have been the better team with better arguments. Hence, challenging is a slightly risky proposition and not frequently resorted to.

Preparation for the debate

Both sides get approximately 15 minutes to prepare for the debate after the motion has been selected. There are strict rules concerning what material the teams may consult during this period:
Members are permitted to use printed or written material during preparation and during the debate. Printed material includes books journals, newspapers and other similar materials. The use of electronic equipment is prohibited during preparation in the debate. It should be borne in mind that the use of printed material during a debate could affect a member's manner.

Points of information

Since the British Parliamentary style does not involve one side directly asking questions to the other after all the speeches are over, you have instead points of information. These are directed at the person who is speaking anytime between the end of the first minute of his/her speech to the end of the sixth minute of the speech (keeping in mind that all speeches are 7 minutes in duration). Now this is where it begins to get ludicrous! The person who is putting forth the Point of Information must stand up, place one hand behind his head, and point the other to the speaker and say that he wants to introduce a Point of Information!. The Member who is Speaking may or may not accept a POI but you must answer at least two such POIs in the course of your speech. They are crucial to your team's points and can also demonstrate the holes in your opponent's arguments. The person to whom the question is being asked, may ask the questioning Member to sit down if he thinks he's heard enough of the question- but the questions are usually not supposed to be more than 15 seconds in length.

Timing and Adjudication

The Speaker times the speeches and will provide a warning bell, usually one minute before the end. Those who substantially overstep the time limit are penalised. Adjudicationn is carried out by a panel of judges according to a set criteria. They may confer at the end and place the teams in ranking order. There is no verbal adjudication and the results of the debate are not immediately known to the teams.

Manner, Matter, Method

The 3 Ms are what debaters are usually judged upon. As far as manner goes voice modulation, and eye contact are key features- don't drone on and one! But usually as long as you are clear and coherent it's fine. Matter is obviously the most crucial element and you are judged upon the soundness of your argument and the evidence you can provide to back it up. Finally, in terms of the structure of the debate, teams adopt their own structure, but judges must be able to see how the arguments flow from one to another and even if you don't have an explicit structure must be able to discern that there is some logic to your madness!

These are the very basics of British Parliamentary debating. There are many other intricate rules relating to definitions, challenges and so on. If you're participating in a competitive debate based on this format for the first time, you'll be well advised to read the official rule book for any changes to this standard format. There are a number of websites that offer help on British Parliamentary debating and contain a list of interesting motions that might want to use to practice. Go to http://www.debating.org.za/rulesbp.shtml and http://www.debating.net/flynn/genguide.htm if you want more help.