It depends on the local by laws and also the markings on the road. Generally you are ok on single yellow and double yellow lines.If however there are stripes painted on the edge of the pavement indicating no loading then you can be booked.
In some areas where street parking is by ticket machine then disabled badge holders also have to pay.Non compliance can mean a ticket or towing away.
Disabled badge holders should read the plates accompanying yellow lines and also notices where payment at a meter is required to be sure they park legally
Also if the vehicle is badly parked or deemed to be causing an unnecessary obstruction then it can be booked/towed away.