Former foreign minister Surapong Tovichakchaikul has been sentenced to two years in prison for issuing a passport for Thaksin Shinawatra.
The court for politicians on Tuesday ruled him guilty of malfeasance under Section 157 of the Criminal Code and the 2000 anti-corruption law.
Since he planned to appeal, the court later approved his request for temporary release on a bond of 5 million baht.
Prosecutors filed the suit against Mr Surapong, who was also deputy prime minister in the Yingluck Shinawatra government, in March last year after the NACC found the case had ground a month earlier.
He was released on bail during the trial on a bond of 3 million baht and was prohibited from travelling abroad.
The court on Tuesday found Mr Surapong, 65, had prepared to issue the passport for Thaksin from the application stage. He had a role in the review and removal of Thaksin's name from the list of people who must be checked before a passport can be given. Such actions violate the 2005 passport regulation, it said.
"The defendant cited a government policy which did not exist. His actions led to the issuance of the passport. This means the defendant, as a minister, aided and abetted Thanksin, who was on an arrest warrant on national security charges " the court said in a statement.
His actions allowed Thaksin to travel freely and live abroad and the Thai government could not ask a country to expel or extradite him on the charge of not having a passport, read the statement.
"This weakened the judicial procedures and court sanctions. It also tarnished the reputation of the country."