Hundreds of thousands of ultra-Orthodox Jews protested in Jerusalem Sunday against a law that would require them to serve in the military and end a generations-long tradition of military exemption for the most religious Israelis.

The protests choked streets in Jerusalem with teeming masses of Haredim, a Hebrew term that means ’those who tremble before God,’ wearing black hats and coats, the traditional Haredi garb, CBS reports.

The new law would suspend military exemptions for Orthodox Jewish seminary students, who are currently excused from serving in the Israeli army. The law, which has been in the works for months and would institute universal conscription at 18, would be implemented in four years time and could be overturned in the interim. 

The debate on ultra-Orthodox service in the army is a heated one. Haredi claim it violates their religious right to study the holy scriptures, a foundation of Jewish life. But some Israelis say the Haredi, a rapidly growing demographic that represents 10% of the country’s population, need to share the burden of military service.