It's probably not illegal, but I certainly wouldn't recommend it. Doing so would lead to a fair amount of harassment from the cops would be my guess. I would question your motivation in engaging in such behavior, as annoying as it may be to go through a checkpoint. On the other hand, if you've got nothing to hide, they are merely a temporary inconvenience. Good luck with whatever you decide to do.
I dont think its illegal and is likely protected speech under the 1st amendment (assuming you are several hundred yards away and not obstructing the checkpoint at all). However an aggressive cop might disagree and arrest you for pc 148 and claim that you were delaying or obstructing a police officer in the lawful performance of his duty. A DA might agree with this and charge you, the cops may lie and exaggerate to make their case against you. Understand that you will be approached by law enforcement, asked for ID, and questioned. Good luck with your protest efforts.
I don't know whether it is necessarily illegal or not. Seems like it would be a free speech protection. I would anticipate that you would have issues with the officers. It is possible that they would arrest you for a PC 148, obstructing charge. I am not saying they should or would, but I certainly see it as a possibility, and then you would have to deal with that. There may be other issues that come up as well. I would be shocked if officers didn't approach you and question you at the very least.
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You may be charged you with PC §148(a)(1) Resisting, Delaying, or Obstructing an Officer. One possible First Amendment defense would be to apply the standard adopted in City of Houston, Texas v. Hill, 482 U.S. 451, 465 (1987), that the police should not have unfettered discretion to arrest individuals for words or conduct that annoy or offend them. The First Amendment also protects individuals where evidence has shown that there is "a mere interruption of a policeman while in the line of duty."
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