For the second summer in a row, political unrest has returned to the streets of Hong Kong.

Hundreds of protesters were arrested in the busy shopping district of Causeway Bay on Wednesday, July 1, after China’s central government imposed a national security law on the semi-autonomous city. Protesters and police clashed in both May and June after a security law was first proposed.

The new law drastically expands the powers of local and land authorities to investigate, prosecute and punish disagreements.

Critics say the law has deprived Hong Kong of its autonomy and precious civil and social freedoms. Chinese and local authorities argue that it is necessary to suppress the unrest and support the sovereignty of the mainland.

Last summer, anti-government protests were fueled by strong opposition to the proposed extradition law. Critics feared the bill would allow citizens to enter mainland China across the border. Hong Kong CEO Carrie Lam withdrew the bill in September, but refused to give priority to four other demands, which include greater city democracy and an independent commission in police action.