Not United, but Delta:
Delta Air Lines kicks US family off flight after row over toddler - BBC News
A family of four got kicked off a plane, after being told that they couldn't let their 1-year-old sit in his own seat with a carseat. Delta wanted them to give up the seat to a standby passenger, and told the family that the carseat and 1-year-old violated FAA laws/rules.
The crew member and Delta rep that showed up to "handle" the situation first told them that if they didn't comply and give up the seat, that they would be jailed and their children would be placed in foster care.
The crew member then called for police. The guy was polite the whole time, and told the officer that if it meant the plane could take off, he would hold the toddler in his lap and give up the seat, despite paying for it.
The crew member then told them that this was no longer an option, and that the whole family needed to leave the flight. They didn't offer to help the family find lodging or anything, only telling them that they were on their own.
Interesting for a few reasons:
Delta personnel first threatened the family over violation of an FAA "law" that doesn't exist.
Second, Delta itself recommends that parents purchase seats for children under two years of age, that way you can bring a car seat and provide your child with the safest flight possible. So in this case, the Delta employee was directly contradicting Delta's own policy.
Third, the flight was overbooked, so when the family left, all four seats were immediately filled.
So, either the employees didn't know their own regulations, or else they were blatantly lying about their regulations in order to squeeze one more person onto an overbooked flight. Even worse, if they were blatantly lying, was that the employee went to fear tactics at one point.
I wouldn't have handled it as well as this guy did.
Also, props to the cop that showed up and tried to smooth things over and get the flight off the ground.