If the court accepts the case filed by the Democrats, it will have to issue an injunction against the April 23 by-elections, which are to be held in constituencies where candidates who ran unopposed on April 2 failed to receive 20 per cent of the eligible votes, the minimum for solo candidates to win a seat.

An injunction would put the outcome of the April 2 election in limbo, as the old candidates will still have to win the 20-per-cent minimum.

As a result, a new House of Representatives would be unlikely to see all 500 seats filled, a requirement for convening its first session.

Thaworn Senneam, the Demo-crat deputy secretary-general who took the case to the court, expects a judgment today, but a court official yesterday said an exact date had not been scheduled for a decision.

"We'll witness a crisis of confidence against the EC if the Central Administrative Court is to accept the case," said Kiat Sittheeamorn, a member of the Democrat Party.

The EC has been subject to severe criticism for arranging election booths in such a way that voters could be observed marking their ballots. It has also been charged with ignoring complaints that smaller parties had been bought to take part in the April 2 election.

If the Central Administrative Court throws out the case as falling beyond its authority, the April 23 election will go ahead as planned, but if the court decides to hear the case a legal debacle could ensue.

"The Democrat Party saw the EC's decision as a potential legal quagmire and sought to exploit it by filing the case with the Central Administrative Court challenging the EC's authority to allow new candidates," said a report by Phatra Securities.

"If the Central Administrative Court agrees that the EC has exceeded its legal authority, the April 23 election would be blocked. The EC is likely to appeal to the Supreme Administrative Court to lift such an injunction. Alternatively, the Central Administrative Court could agree with the EC in which case the Democrats are likely to appeal to the Supreme Administrative Court for a final verdict on the case."

Last week the Democrats filed a case with the Central Administrative Court to block the April 23 by-election, arguing that the EC's decision to invite new candidates to run in the 40 constituencies violates the election law. They also argued that the EC could only invite new candidates to stand in the repeat elections if it could secure a new decree for another election.

Commissioner Prinya Nakchudtree said the EC would submit its case to the Constitution Court if the Central Administrative Court rules against its legal authority to hold repeat elections.

He argued that holding repeat elections lies within the scope of the EC.

"I would like to insist that the EC has conducted itself within the legal boundaries. But if the Central Administrative Court nullifies the application of the new candidates standing in for the repeat elections, the EC would submit its case to the Constitution Court, which will be asked to rule on the EC's authority," Prinya said.

Phatra Securities added that if the Democrats win their case, the EC would then be forced to hand in the election results to the caretaker government with only 461 MPs out of the total 500 MPs needed.

The caretaker government would have to ask the Constitution Court whether this election result, with only 461 MPs, is completed or not in order for Parliament to convene.

"If the Constitution Court rules the election results to be completed, then Parliament can open, allowing the MPs to pick the next prime minister. Politics will then be back on track with risks considerably reduced," the report said.