How many technicals have you called this year?

[thereluctantref]

I have a question...has anyone ever called a technical on a fan? I was coaching this year (5th and 6th grade boys basketball) and a fan/parent was arguing/"commenting" on every little call that went against his son's team. It was very distracting to our team and very nasty as far as sportsmanship goes. This went on the whole 2nd half practically. The referee finally went to the coach and warned him to control the fan or else he would give the team a technical. Could he have rightfully done this? Also, what is the point at where you draw the line for fans? How far can they be verbally abusive?
Thanks!