From Yahoo News (Reuters):
In a survey of a random sample of U.S. emergency physicians, virtually all said they believed that law enforcement officers use excessive force to arrest and detain suspects.
The sample included 315 respondents. While 99.8 percent believed excessive force is used, almost as many (97.8 percent) reported that they had managed cases that they suspected or that the patient stated had involved excessive use of force by law enforcement officers.
Nearly two thirds (65.3 percent) estimated that they had treated two or more cases of suspected excessive use of force per year among their patients, according to a report of the survey published in the January 2009 issue of the Emergency Medicine Journal.