I can't say for UC Davis, but even at most campus's there are steps required to have a formal protest. Its a simple notification to Student Life or Admin that its being planned out before hand. Even if those steps weren't followed, the protest would still probably be allowed. However, if said protest disrupts services at campus then yes, you could be arrested depending on state or local law. For example Columbus Code: 2317.11 - Disorderly conduct. (A) No person shall recklessly cause inconvenience, annoyance, or alarm to another, by doing any of the following: (1) Engaging in fighting, in threatening harm to persons or property, or in violent or turbulent behavior; (2) Making unreasonable noise or offensively coarse utterance, gesture, or display, or communicating unwarranted and grossly abusive language to any person; (3) Insulting, taunting, or challenging another, under circumstances in which such conduct is likely to provoke a violent response; (4) Hindering or preventing the movement of persons on a public street, road, highway, or right-of-way, or to, from, within, or upon public or private property, so as to interfere with the rights of others, and by any act which serves no lawful and reasonable purpose of the offender; (5) Creating a condition which is physically offensive to persons or which presents a risk of physical harm to persons or property, by any act which serves no lawful and reasonable purpose of the offender. The protest was loud as one would expect, and if that disrupted class rooms or services on campus, #2 applies. Also, by them screaming profanities at the Police, other civilians/passerby's very well could be offended by it. Also, if by means of encircling the area on the block, that hindered or prevented movement of persons to and from, then #4 could possibly apply. I would say the charges were dropped due to the bad publicity in the media and the school trying to save face. As for the obstruction... (same scenario) The officers in the middle have arrested several protesters and are trying to exit the area with those arrestee's. The protester's have now encircled the police and are preventing them from leaving with said arrestee's and demanding the released. The officers have told them to move repeatedly and yet the protester's sat down to block the officers from leaving. Ohio Revised Code: 2921.31 Obstructing official business. (A) No person, without privilege to do so and with purpose to prevent, obstruct, or delay the performance by a public official of any authorized act within the public official’s official capacity, shall do any act that hampers or impedes a public official in the performance of the public official’s lawful duties.