Simplify the following text for a Grade 12 native English-speaking person.
Original: In the case , a legislative amendment to disqualify from voting all prisoners ( as opposed to only those serving sentences of three years or more , as it was before the amendment ) was struck down as contravening that right .
Simplified: In the case , a legislative change to stop all prisoners from voting ( as opposed to only those serving sentences of three years or more , as it was before the amendment ) was rejected as breaking that right .