The EU is trying hard to find a replacement for the European constitution, two years after its rejection in referendums in France and the Netherlands.
Germany, which holds the presidency of the EU Council of Ministers until the end of June, is leading the effort to find a way out of the impasse, aiming for final adoption of a new treaty by mid-2009.
It is hoping to get agreement on the main parameters of the treaty at a summit in Brussels on 21-22 June, and to agree a precise mandate for a conference to decide on the final text.
What is the status of the constitution at present?
It is on hold.
It has been fully ratified by 16 of the 27 member states, and nearly ratified by two others. But it cannot come into force unless it is ratified by all 27 - and two have rejected it.
What options are on the table?
Some of the countries which ratified the draft constitution would like the new treaty to be a copy of the original text, with only cosmetic changes.
But a proposal for a much shorter treaty - the original draft stripped down to its bare essentials - has been gathering support. Some politicians like this idea, because they think most countries would be able to ratify a cut-down treaty without holding referendums.
The experience of 2005 shows that referendums can cause upsets, even in founder members of the EU. A referendum in a country like the UK or Poland would be even more likely to result in a "No" and throw the union back into crisis.
What parts of the constitution would be dropped, in a shortened treaty?
This is currently the subject of vigorous debate.
It is generally accepted that it was a mistake to call the treaty a constitution, and that the new version should not mention the EU flag, anthem or motto.
The proposal to have a "foreign minister" answerable to member states, but with a seat on the commission, would remain in the treaty, but the post would be renamed to eliminate any whiff of an EU "government" taking shape.
The UK is leading the fight to limit the scope of the treaty - it wants an "amending treaty" that tweaks earlier treaties rather than a grand project to merge all earlier treaties into one new whole. It wants to avoid a big shift towards more majority voting (in areas such as justice and home affairs), and is against the EU acquiring a "legal personality", which would allow it to join international organisations.
It also wants to keep the EU's non-binding Charter of Fundamental Rights, signed in 2000, out of the treaty.
What would be left in a shortened treaty?
This is part of the same debate, but any new treaty can be expected to include the key institutional changes from the original draft:
- A full-time president, to replace the system where member states take it in turns to hold the presidency of the Council for six months
- A smaller commission, in which not every country would be represented by a commissioner
- A "foreign minister" under a different name, with an "external action service" to assist him or her
- A new system for voting, when member states take decisions that do not require unanimity.
Of these measures, the new voting system - which would link voting power more closely to population size - is the most controversial. Poland is vehemently opposed, because Poles voted to join the EU in 2003 on the basis of the Nice Treaty, which gave it stronger voting powers. Poland has argued instead for a system that would link voting weights to the square root of a country's population.
The Eurosceptic Open Europe think-tank also points out that the new voting system makes it harder to block EU legislation. It says the UK's ability to block legislation would be diminished by 30%.
Would anything be added to the treaty?
There has been talk about adding a "social protocol" to the constitution, to dispel the widespread view, in some countries, that the EU is all about free markets - good for business and bad for workers.
Some have also suggested that the treaty should say something about energy policy and climate change, which have become priority areas for the EU since the original text was drafted.
The German presidency of the EU has proposed adding a measure allowing countries to opt out of joint policies on policing and criminal justice, while allowing others to go ahead; a measure to strengthen the power of national parliaments to get the commission to reconsider policy proposals; wording that makes clear that EU powers can be reduced as well as increased in future treaties.
Does the EU need a new constitution?
The British, Czech and Polish governments say the EU has been able to work quite well without it. However, many other states do not understand this point of view. They say the EU cannot move forward until it clears this major piece of unfinished business and acquires some new powers.
British officials agree that it would be good to streamline some of the EU institutions, but they say there is no hurry, and that it could be done by tinkering with existing treaties.
What is the timetable for further action?
The Berlin Declaration adopted in March 2007 called for institutional changes to be completed by the European Parliament election in mid-2009.
The German EU presidency will propose a timetable and suggestions on the substance of the future treaty at a summit in June 2007.
If all goes well, the summit will issue a mandate for an intergovernmental conference to agree the new text in the second half of 2007. Ratification would then take place in 2008.
What will happen if attempts to agree a new treaty collapse?
The EU will be plunged into a political crisis again, as it was in June 2005. Enthusiasts for European integration may start lobbying more vigorously for the idea of a two-speed, or multi-speed, Europe.
There are also a couple of areas where existing treaties leave the EU with awkward issues to resolve.
The Nice Treaty agreed in 2000 decrees that the European Commission should be slimmed down in 2009, so that there is no longer one commissioner per country. A decision will have to be reached on this question at some point.
Also, existing treaties provide for an EU of no more than 27 states. So, either enlargement will have to stop, now that Bulgaria and Romania have joined, or the treaties will have to be amended.
The UK says that both problems could be solved by tacking some extra paragraphs onto the accession treaty of the next country in line to join the EU, Croatia. But countries that favour deeper EU integration could block further broadening of the EU until the constitution is adopted.
What was the constitution meant to do for the EU?
The constitution paved the way for the EU to become more integrated in many areas while leaving veto rights with member states in such key matters as foreign policy, taxation and defence. It represented one solution to the perennial question facing EU states - how much sovereignty to pool - and might have put the issue to rest, at least for a while.
Supporters said the constitution would have streamlined EU decision-making, strengthened its ability to project its weight on the international stage, and helped it to develop new policies in a key growth area - justice and home affairs.
Why did the French and Dutch vote 'No'?
The French did so partly as a protest against their national government, especially over the economy, but they also had problems with the treaty itself.
On the left, many voters believed that the constitution would create an ultra-free market economy within the EU. On the right, voters were concerned that France was ceding too much sovereignty to the EU.
The Dutch shared some of these fears, but were also concerned about the place of the Netherlands in an enlarged EU, fearing the effects on a smaller member state with liberal traditions.
Which countries have ratified the treaty already?
Austria, Belgium, Bulgaria, Cyprus, Estonia, Finland, Greece, Hungary, Italy, Latvia, Lithuania, Luxembourg, Malta, Romania, Slovenia and Spain.
Two countries - Germany and Slovakia - have completed the parliamentary stage of ratification, but the ratification instruments have not been signed.
What about the other countries?
The Czech Republic, Denmark, Ireland, Poland, Portugal, Sweden and the UK have put ratification on hold. In Ireland, ratification cannot take place without a referendum. In the other states there is some political room for manoeuvre.
French President Nicolas Sarkozy was the first to lobby for a short treaty - or "mini-treaty" as he originally called it - which would be ratified by the French parliament.
It is still unclear whether the Netherlands - the other country that rejected the constitution in 2005 - will hold a referendum on any new treaty.