Pro-democracy candidate Lau Siu-lai, who had previously been disqualified from the Legislative Council over her oath-taking, was barred from running in the November 2018 Kowloon West by-election. The returning officer invalidated her candidacy on the basis of Lau previous advocacy of Hong Kong's self-determination, which showed "she had no intention of upholding the Basic Law and pledging allegiance to Hong Kong as a special administrative region of China."