The handicapped marked vehicle may only use the handicapped marked space when the handicapped person is present.
I occasionally drive my MIL's van ... complete with (deserved) handicapped plates. If she's present, I park it in the handicap spot. No fuss, no foul.
If she's not, I have two choices.
1) Park in a handicap spot, and VIOLATE THE LAW (as well as be a jerk). Not gonna happen, bro'.
2) Park in a 'regular' space, and generate stupid comments from ignorant morons who like to vent their spleens on pseudonymous internet forums.
Thank you. As expected, you have a much more ethical character than do my Obama-voter in-laws who see a Handicapped license plate as carte blanche.
OH COME ON! It was obviously a joke! Now what really want to see is some getting towed for parking their rear in a handicapped toilet stall without a decal!