In chapter nine of the Sorcerer's Stone, Harry breaks the rules by flying a broom immediately after being ordered not to do so. The rule had been set in place moments before Harry chose to break it and was set for the safety of Harry and the other children. Because Harry turned out to be a natural on the broom, a good end, his breaking of the rule, the means, was justified. According to the end of chapter ten and the beginning of chapter eleven, the close friendship between Harry, Ron and Hermione begins in part because Hermione is finally willing to lie and break the rules. As the story develops we see Harry, Ron and Hermione breaking rules, sneaking into forbidden parts of the school, and lying. But, since it all works out in the end, it's OK. Is that the lesson we want our children to learn?
Possibly. When I was a college professor, the college I worked for pressured every student to sign a pledge that they they would not cheat or plagiarize. A certain number of students might refuse to sign this pledge because they wanted to get away with cheating. But others refused to sign because they simply opposed the idea of taking a pledge that was being forced upon them by the institution. Personally, I was very proud of this second group, even though they were in league with cheaters. But I guess that's what distinguishes lbertarians from moralists.
Given the corrupting nature of power, we should always be quick to question authority and rules. Didn't George Washington break the rules? Didn't Mozart break the rules of music in his day? True greatness comes not from going along, but from having the courage to ask why a rule exists, then deciding whether or not it deserves to be broken. The best example I can think of is if the federal government decided to confiscate our guns. Isn't that a rule we would be morally obligated to break?
As for Potter, I was a bit perplexed as to why he was not reprimanded for flying that broom after he was told not to. But I think the point is that true excellence can supercede rules, and that is a point worth considering. Had some stupid kid grabbed the broom and hurt himself, he would have paid two prices: pain and repurcussions. For better or worse, that is the true nature of life.