Crime Suppression Divison police took Mr Worachet to the Bangkok Military Court and asked permission to detain him for 12 days for questioning, after charging him with defying a summons from the National Council for Peace and Order (NCPO) to report to military officials.
Mr Worachet reported to the NCPO on Monday after returning from Hong Kong and was handed over to the CSD by a military escort on Wednesday morning.
The court initially approved the police request to detain the academic, but later allowed his released after his lawyer applied for bail, offering 20,000 baht as surety.
The bail was granted with the condition that Mr Worachet must not join or get involved in political rallies. He is also prohibited from travelling out of the country without the court's permission.