The Diet enacted a controversial law Thursday on procedures for hospitalizing mentally impaired lawbreakers, after an unusually long path of deliberation.

The House of Representatives passed the bill with primary backing from the ruling coalition. The new law is expected to take effect next spring at the earliest.

The government proposed the legislation during last year's ordinary Diet session. But the opposition camp argued it could lead to prolonged hospitalization because it fails to clarify concerns over the recurrence of crimes, leading it to undergo deliberations for three legislative sessions.