At the moment, motorists' selfishness in parking on pavements illegally goes unpunished, and dangerous siyuations frequently arise when pedestrians, wheelchairs, pushchairs etc are forced out into the traffic. My suggestion would made the prosecution of offenders much easier.
Parking of vehicles on pavements should only be permitted if a gap is left wide enough to allow a wheelchair, disabled buggy or pushchair to pass on the pavement – perhaps a gap of 4ft/1.2metres; leaving a gap of less than this would constitute an offence. At the moment, I believe obstruction has to be proved, which seems to be sufficiently difficult to rule out any prosecutions from ever being made. Motorists therefore park on pavements with impunity, forcing people to move out into the traffic. Specifying the size of gap to be left would make proof of an offence being committed quite straightforward.