The security was stepped up in the morning in advance of the rally on Monday evening of red-shirt community radio operators in front of the court at the Government Complex.
The so-called Democratic Force group was also rallying in front of the court to provide moral support to the constitutional court judges.
Police put up barricades at the stairways of the court and at the front gate. Police also used prisoner trucks to block the entrance to the court and prohibited parking in front of the court.
Chaowana Traimas, the secretary general of the Office of the Constitutional Court, said the court had sought help from police to step up security ahead of the ruling.
Police were deployed to keep security both inside and outside the court’s compound, Chaowana said.
He said the judges were not worried about the demonstrations by various groups and the venue for the verdict reading would not be changed.