Even though Japan's adult guardianship system may be necessary to protect the assets of those who need additional attention due to their mental state, stripping them of their suffrage is an excessive infringement of rights that goes against international trends, experts said.

Thursday's ruling that the Public Office Election Law takes away the voting rights of the disabled and the elderly with dementia is "unconstitutional" cast the spotlight on the fact Japan lags behind the global community in protecting the rights of those with certain disabilities.

The guardianship scheme was first introduced in 2000 to help people with cognitive disabilities manage their assets. It replaced a system dating from the Meiji Era that prevented those declared incompetent from having control over their own property and was often criticized as discriminatory because details of their disability was officially entered into the family registry.