Key legal question
Whether the insurer could reassign the insured to a higher premium bracket under the new age-group scheme based on the restructured tariff
Extracted holding
The reassignment was unlawful because premium brackets must be based on the insured's effective entry age, not on a later transitional cutoff.
Extracted reasoning
The court held that the mutuality and equality principles require equal premiums for equal risks and benefits, subject only to the exhaustive statutory exceptions. For age-based premiums, Art. 17 of the ordinance ties the relevant age to the moment of entry into the fund; a later tariff reform cannot create a different age classification for existing members who entered at the same age as new members in a lower bracket.