SCENARIOS - Obstacles to EU's Lisbon reform treaty

(Reuters) - The European Union's Lisbon reform treaty, intended to give the bloc more global influence and streamline its decision-making process, still faces some hurdles before it can go into force.

The treaty requires the approval of all 27 member states to take effect but has not yet been ratified by the Czech Republic, the only country that is still holding out against it.

The Czech parliament has backed the treaty but President Vaclav Klaus has opposed it. He is awaiting a ruling by the Czech Constitutional Court on whether the treaty is in line with the country's constitution.

Klaus has also asked other EU leaders for the Czech Republic to be given an opt-out from a rights charter that is attached to the treaty.

EU leaders are expected to discuss Klaus's demand at a summit on Thursday and Friday.

The following are possible scenarios of what could happen.

COURT REJECTS APPEAL AGAINST TREATY

The Czech Constitutional Court is due on Tuesday to consider a complaint against the treaty by Klaus's allies in the upper house of parliament, the Senate.

The senators say the treaty takes away national sovereignty and is at odds with the Czech constitution.

Most lawyers say the court, which has already rejected one appeal by the Senate, will throw out the senators' challenge.

It could issue its ruling on Tuesday or take longer to do so. Czech Prime Minister Jan Fischer said on Monday he did not expect the final ruling until later.

Rejection of the appeal would give Klaus the legal authority to sign the Lisbon treaty -- he cannot sign before the ruling.

COURT ACCEPTS APPEAL

Court acceptance of the appeal would be a big surprise that would complicate the picture. The Czech constitution would have to be changed to allow ratification. This would be a lengthy and uncertain process.

OPT-OUT DEMAND

Klaus says a Czech opt-out from the Charter of Fundamental Rights, which is attached to the treaty, is needed to protect the Czech Republic from property claims by Germans expelled from the former Czechoslovakia after World War Two.

Poland and Britain have already negotiated opt-outs from the rights charter, but did so during negotiations on the Lisbon treaty.

Most lawyers and political analysts say Klaus's concerns are unfounded and that the demand may be a face-saving exercise because he has criticised the treaty so loudly.

The Czech government has been negotiating with Sweden, which holds the EU presidency, on Klaus's demand.

The most likely way forward is that EU leaders give the Czechs a political guarantee at the Brussels summit on Oct 29-30 that promises them the opt-out. This would not mean changes to the treaty itself and the opt-out could be slipped through in the next EU treaty, possibly when the bloc next takes in a new member state. The country expected to join next is Croatia.

If Klaus does not secure agreement on the opt-out, he could refuse to sign the treaty. But the chances of a deal being reached rose on Friday when Klaus welcomed an EU presidency proposal, although details were not released.

Klaus has also said the treaty has already gone too far to be blocked.

OTHER HITCHES?

Another problem could be raised by Slovakia, even though it has already ratified the treaty. After Klaus sought an opt-out, Slovakia said it may make a similar demand because Hungarians were expelled after World war Two under the same legislation.

The Slovaks could try to block any opt-out that is agreed for the Czechs if they decided to press ahead with such a demand and did not get what they wanted, but would face huge pressure from other EU member states that would make this difficult.

Klaus could try to delay signing the treaty until after a parliamentary election in Britain next year because opposition leader David Cameron, who is widely expected to become prime minister, has said he will hold a referendum on the treaty if it is not ratified by all member states by then.

But Klaus has already indicated he would not hold out until then and the likelihood of him being able to do so has diminished.

(Compiled by Jan Lopatka)