Hong Kong’s top court has been asked to abolish an “extraordinary” and “inexplicable” law prohibiting calls to boycott the city’s “patriots-only” elections on the grounds that it violates residents’ rights to express disapproval of the political system and to make informed decisions before voting.

A government senior counsel opposed the challenge by former Chinese University of Hong Kong student union president Jacky So Tsun-fung, arguing the law fell outside the scope of constitutional review. He cited Beijing’s decision to address “clear loopholes and deficiencies” in the electoral system after the city’s 2019 anti-government protests.

The Court of Final Appeal on Wednesday examined the legality of Section 27A of the Elections (Corrupt and Illegal Conduct) Ordinance, which took effect in May 2021 as part of a broader Beijing-led electoral reform aimed at ensuring only those deemed patriotic by authorities could hold public office.

So received a suspended jail sentence in December 2022 for reposting a social media message urging Hongkongers to cast blank votes in the Legislative Council election the previous year.

He initially challenged the legality of the charge but later pleaded guilty after a deputy magistrate ruled that the ban on inciting others to boycott or cast invalid votes during specified election periods was constitutional.

The Court of First Instance dismissed an appeal stemming from that constitutional challenge last year.