HONG KONG—Hong Kong’s top court denied bail on Tuesday to media tycoon and Beijing critic Jimmy Lai, the most high-profile person to be charged under the city’s national security law. Lai had been in custody since Dec. 3, except when he was released on bail for about a week late last year. He was granted a HK$10 million ($1.3 million) bail by a lower court on Dec. 23 only for the Court of Final Appeal (CFA) to bring him back into custody on Dec. 31 for another hearing following an appeal by the government. His return to custody was related in part to Article 42 of the security law, which says that “no bail shall be granted to a criminal suspect or defendant unless the judge has sufficient grounds for believing that the criminal suspect or defendant will not continue to commit acts endangering national security.” On Tuesday, the CFA’s …