Protests against the reform have been held in Israel for 12 straight weeks.
On Saturday, nearly 300,000 demonstrators gathered in Tel Aviv alone, The Times of Israel reported, saying that overall 630,000 people took to the streets across the country.
According to the newspaper, police used water cannons against demonstrators in Tel Aviv.
At least 28 protesters were detained while blocking the Ayalon Highway in Tel Aviv.
In January, Israeli Justice Minister Yariv Levin rolled out a legal reform package that would limit the authority of the Supreme Court by giving the cabinet control over the selection of new judges, as well as allowing the Knesset to override the court's rulings with an absolute majority. In mid-February, the Israeli parliament approved the first part of the legislation. The second half was approved by the Constitution, Law and Justice Committee of the Israeli parliament, the Knesset, at the beginning of March.
The reform's opponents argue it will undermine democracy in Israel and put the country on the verge of a social and constitutional crisis.
On Friday, organizers of the protest movement against the judicial reform in Israel declared a "week of paralysis," which would include nationwide demonstrations against the divisive legislative action.
Earlier this week, hundreds of activists swarmed outside the residences of prominent Israeli government officials — including Tourism Minister Haim Katz, Diaspora Affairs Minister Amichai Chikli, Environmental Protection Minister Idit Silman, and Defense Minister Yoav Gallant, among others — to protest against the judicial reform.