In an unprecedented and scathing decision, an Ontario judge has blocked Premier Doug Ford's plan to slash the size of Toronto city council nearly in half.

Justice Edward Belobaba says Ford's Progressive Conservative government "clearly crossed the line" with its Better Local Government Act, which aligns municipal ward boundaries with provincial ridings, cutting the potential number of councillors from 47 to 25 after the Oct. 22 election.

In his highly anticipated ruling, Belobaba calls the act "unconstitutional."

"Passing a law that changes the city's electoral districts in the middle of its election and undermines the overall fairness of the election is antithetical to the core principles of our democracy," Belobaba says in his written decision.