This will be my last post for close to three weeks. I'm heading out of the country (hiking in Greece).
The late-breaking news is that six BPD officers have been criminally charged. That's a lot. This will be a very tough case for the prosecutor to win. The most serious charges need intent (said a law professor I was just on the radio with). Intent beyond negligence or indifference.
The other detail well worth mentioning is that, according to the state's attorney, Gray had not committed a crime. The knife was legal, she said. Hence there was no probable cause for arrest. (Strangely, though, the Supreme Court has ruled that officers are OK as long as they think something is illegal. But I don't know if that applies to something like this. Best I remember that case was something about a traffic (non) violation and a subsequent search.)
So legally, best I understand, the initial chase and stop were legal (reasonable suspicion based on flight from police). But there was no probable cause for arrest because Gray wasn't doing or carrying anything illegal. Fleeing from police gives reasonable suspicion to stop (and a frisk leads to plain-touch with regards to the knife; that plain-touch then gives probable cause to search for said object; and the knife would be legally found). But if the knife isn't a crime... well, you don't have probable cause for arrest. That's minor compared to the more serious charges, especially if you think the knife is illegal, but it certainly does not help the police.