The Constitutional Court on Wednesday ruled the bill on the selection of senators passed by the National Legislative Assembly (NLA) is legal.
All court judges agreed that the bill did not violate the 2017 constitution, the court said.
The ruling followed a petition signed by 30 people, mainly NLA members, who fretted about its legality, saying it could pose legal problems later if its constitutionality remained unclear.
The centre of the problem was clauses that allow for senate candidates to propose themselves, organisations to field candidates for selection, and require intra-group selection among candidates instead of cross-group voting.
This raised questions over whether the selection process contravened Section 107 of the charter, which stipulates that senators must be installed from selections made by and among candidates.
The court confirmed in its judgement on Wednesday that the clauses were in line with the constitution.
Next for the court is a ruling on the election of MPs and its constitutionality, which was set for May 30 after it was discussed by the judges on Wednesday.
The two organic laws, which have passed through the NLA, are crucial for a post-coup general election. The government has a tentative plan for polls in February next year, and no sooner, with pressure from activists for a clear timeline.
Deputy Prime Minister Wissanu Krea-ngam said before the court's judgement that the ruling on the two bills was not an impetus for the elections to be held sooner, because there were more factors to consider.
Jade Donavanik, legal adviser to the Constitution Drafting Committee, said the ruling could mean there were no stumbling blocks for an election in February. He agreed with Mr Wissanu there was little chance the polls would be organised earlier.
