The protests against Wall Street and the financial establishment have provoked excessive use of force, protesters claim. Is it part of a broader trend in the U.S.?

The Guardian certainly thinks so. The British daily is out with a survey of alleged brutality and racial profiling by police in New York, Los Angeles, Chicago, Miami and elsewhere. Civil libertarians say police are violating rights and defaulting to violence. That's the reason, one told the Guardian, that police are increasingly demanding that passersby not film them making arrests or performing interrogations.

"There is a widespread, continuing pattern of officers ordering people to stop taking photographs or video in public places, and harassing, detaining and arresting those who fail to comply," said Chris Calabrese, of the American Civil Liberties Union. Campaigners say the spread of camera phones is why so many incidents of brutality are appearing.

The hacker collective Anonymous has also alleged improper tactics by police, particularly in cracking down on the Occupy Wall Street movement, as it has spread to cities around the world. The group hacked the website and email addresses of the Boston Patrolmen's Association and other police sites, in retaliation for the break-up of an Occupy Boston protest. The police represent the "corrupt bootboys of the 1 percent," an Anonymous posting declared.

The attack was meant to coincide with the National Day of Action Against Police Brutality, as well as the opening of the convention of the International Association of Chiefs of Police in Chicago, CNET reported.

Finding hard numbers is difficult, however, and it's not clear if the trend the Guardian reports is a statistical rise in bad behavior by police, or an agglomeration of well-publicized events. Some, like this shooting of an unarmed man in New Jersey, are nebulous cases, where the truth about the actions of police and victims will likely never be known.

And even in cases of reported abuse, there is no central repository of data to be studied, analyzed — and, perhaps, protested. One of the Guardian's experts explains:

"The problem is that there is an absence of research," said Professor John Liederbach, an expert in American policing at Bowling Green State University in Ohio. As the list of complaints and incidents grows, that might be about to change.