Anti-mask law does not violate human rights
According to Hong Kong's Public Order Ordinance protesters can be prosecuted for unlawful assembly if they conduct themselves in a disorderly, intimidating, insulting or provocative manner intended to or likely to commit a breach of the peace. It is immaterial that the original assembly is lawful if being assembled they conduct themselves in such a manner, as they will then be guilty of unlawful assembly.
The Ordinance also states that any person taking part in an unlawful assembly who commits a breach of the peace is guilty of rioting.
However, the two offences require a high standard of evidence for conviction. A number of individuals have been arrested during the protests on these charges, but the Department of Justice has chosen not to prosecute due to insufficient evidence.