Guest blogged by Ernest A. Canning, with Brad Friedman

In the wake of a violent, night-time confrontation with Occupy Oakland demonstrators last week by the Oakland Police Department (OPD) and some 15 other law enforcement agencies, questions have arisen about the legality of the tactics used by the agency during mass arrests which led to serious injuries, including the fractured skull of a two-tour Iraq vet.

Oakland's Interim Police Chief Howard Jordan has maintained that the use of chemical agents and other so-called "less than lethal" weapons were required in order to defend law enforcement officials from demonstrators.

However, a forensic analysis by The BRAD BLOG of video taken immediately prior to and during last week's raid and confrontation with Occupy Oakland demonstrators, creates doubt about the legality of the OPD decision to declare the demonstration to be an "unlawful assembly," and, in particular, raises serious questions about the veracity of the Interim Oakland Police Chief's claim that police "had to deploy gas in order to stop the crowd and people from pelting us with bottles and rocks."

Moreover, evidence in several of the videos suggests that the multi-agency task force may have violated both CA Penal Code Section 407 and an OPD Training Manual [PDF] that had been adopted pursuant to a federal consent decree signed by the Oakland PD after another confrontation with protestors some years ago.

That federal consent decree was the product of litigation initiated after a brutal assault on a 2003 anti-war protest at the Port of Oakland, during which, according to civil rights attorney James B. Chanin, OPD not only deployed so-called "less than lethal firearms," but ran over demonstrators with motorcycles, and shot and arrested longshoreman who were not even a part of the demonstration.

Chanin reports that, during a deposition in the 2003 case, he "discovered" that the OPD had "infiltrated a subsequent demonstration, and even a planned route the demonstrators would take." Video posted at the end of this article shows plain-clothed, under-cover cops mingling with demonstrators at Occupy Oakland, revealing that OPD used similar infiltration techniques during recent demonstrations as well. Audio included in the video captures Interim Chief Jordan bragging about the ease of infiltration.

Yet another video, also posted below, suggests that two-tour Iraq vet Scott Olsen's brain injury was likely caused by a member of the San Francisco Sheriff's Emergency Service Unit (ESU), but, despite reports from activists on the Internet, the identity of that officer is still an open question...

In our coverage of the police assault on peaceful Occupy Oakland demonstrators Wednesday, we ran the inspiring photo of a man standing in front of a line of riot police, wearing a sailor's uniform, holding a Veterans For Peace flag and clutching a copy of the U.S. Constitution.

But what we didn't realize at the time --- not apparent from the photo, but seen in the following, remarkable video --- he was also standing stone still as tear gas canisters were exploding all around him...

I can't help but look at the faces of the police in gas masks, presumably from the Oakland PD (though there were some 17 other agencies there that night) in that haunting video, as they look at the sailor, and wonder what they must be thinking to themselves as that hero stands facing them. We have previously written about the extraordinary violations of the First Amendment that have occurred across the country during these otherwise peaceful demonstrations. What thoughts are going through the minds of those men --- all of whom are undoubtedly also a part of the same "99%" for whom Occupy protesters are fighting --- during that moment?

And, as another photograph now reveals, look who happens to be standing right next to the sailor seen above, in the moments just prior to the Oakland PD's tear gas assault...

Once again, late last night, as is becoming a too-regular nightly ritual, after the 11p news was over, police moved in again to violate the Constitutional First Amendment right "of the people peaceably to assemble." And, for the second night in a row, late last night in Oakland, CA, it resembled a war zone as police in riot gear unleashed a punishing onslaught of "non-lethal" flash-bang grenades, rubber (and or bean-bag) bullets and tear gas --- hour after hour, round after round --- injuring demonstrators, including women, the disabled, and even Iraq War veterans...

Unlike the police in Albany a few nights ago, where they defied orders from NY's Democratic Governor Andrew Cuomo to arrest demonstrators, and more like Chicago, where the police followed the advice of Democratic Mayor Rahm Emanuel to break down the demonstrations over the weekend and haul more than 175 in, the Oakland Police Department, with the approval of Democratic Mayor Jean Quan, unleashed a punishing assault on those gathered "to petition the Government for a redress of grievances."

The results were horrific, according to video, photos, and eye-witness reports as it all happened and was reported on Twitter, including this scene appearing to show a member of Veterans for Peace and Iraq Veterans Against the War knocked out by either a concussive grenade or a tear gas canister or another projectile, and being carried away...

[Update]: The veteran seen above was shot in the head and the UK Guardian is now confirming his name is Scott Olsen and that he is in "critical condition" with a "skull fracture and swelling of the brain" at Highland hospital.

"It's terrible to go over to Iraq twice and come back injured, and then get injured by the police that are supposed to be protecting us," his roommate, Keith Shannon, also 24, who served alongside Olsen as a Marine in Iraq, told the Guardian in a late follow-up today.

Other scenes were similarly gruesome and, yes, shameful...