In this case, Deputy Billings saw his 17 year old neighbor driving without headlights. Billings had had previous enforcement contact with the kid, and thought he might have drugs (although there was no PC for this; all he had was traffic charges). He tried to make a traffic stop, and the kid instead drove home and then ran into his house and hid. There is no mention in the decision of any recklessness that would have given rise to eluding charges. The house apparently only has one entrance (maybe it was a really little apartment?).
Deputy Billings started banging on the door and demanding that the occupants come out. Christina and Jose Mascorro (the kid's mom and step-dad) answered the door. Billings gun-pointed them, demanded to know where that little motherfucker was, etc. According to Billings' testimony, Christina tapped him in the chest with her finger at some point. Christina, Jose, and their 14 year old kid were all pepper sprayed, and Billings made entry into the residence over their objection, kicked the bathroom door in, and arrested the 17 year old who was hiding there. The Mascorros were transported to a hospital for treatment of their pepper spray (apparently over Billings' objection...) and then taken to jail where they were charged with interference. Christina was also charged with aggravated assault on a peace officer for tapping Billings' chest with her finger.
At some point during all of that, officers from the local PD arrived to assist. Testimony conflicts as to when they arrived... the Mascorros say they were there the whole time, the officers say they showed up when shit was already out of control.
Anyway, all charges against the Mascorros were dropped because the court held that there were no exigent circumstances justifying the entry into their home. The Mascorros sued, and the officers involved tried to invoke qualified immunity. The court denied qualified immunity, and the officers appealed.
The Tenth Circuit affirmed, holding that although there was probable cause to arrest the juvie for a traffic offense, this offense was not serious enough to create exigent circumstances on it own. Hot pursuit is generally applied to fleeing felons, although it can also apply to misdemeanants (I think the court made that word up) if there are additional aggravating factors. Hot pursuit into a suspect's home can overcome the presumptive unreasonableness of in-home arrests when it is necessary to prevent the destruction of evidence, or when there is a substantial flight risk, or when the offense is serious, or if there are other officer or public safety concerns. Given that the suspect in this case was fleeing from a warrantless arrest for a minor traffic charge, and that he was already identified, and that he fled into a house with no other exit, and that there was no articulated danger to the public, the court was having none of this hot pursuit. The court held that Billings' entry into the home was unreasonable, and that any reasonable officer in his place would have known this, so he was denied qualified immunity.
There's more. The court held that whether or not the other officers had participated in this violation of a clearly established right was a question of fact rather than a question of law (it depends on when they showed up, and that fact is in dispute). So they were also denied qualified immunity.
Sometimes we are our own worst enemies.