I received a ticket for illegal parking in handicap spot for $250. I was told by the school principal it was ok to park there.

There is no defense to a ticket for illegally parking in a handicap space when you didn't have a handicap permit. If you want to park in that space without getting a ticket in the future, get the permit. Perhaps you could qualify, depending upon how actually special the needs are of your son. That would be up to you along with a physician and the Colorado Department of Revenue, Motor Vehicle Division.

If you don't have a handicapped parking permit, then you can't park in a handicap spot. You may be able to qualify for one because of your son, but without a permit they are within their rights to give you a ticket.

There is a parking ticket referee at municipal court in Colorado Springs who has traditionally been pretty reasonable. Go talk to him about some more reasonable resolution

Unfortunately, the principal gave you inaccurate legal advice. You were not justified in accepting his legal interpretation, so this will not give you a defense to the ticket. However, if you explain the situation to the Court it is likely that you can get the fine reduced since this is the first ticket for this offense.