The opinion of the court was delivered by: Judge Robert M. Dow, Jr.
MEMORANDUM OPINION AND ORDER
Plaintiffs Cesar Martinez and Alonzo Rodriguez brought this action pursuant to 42 U.S.C. § 1983 against Defendants City of Chicago, and Chicago police officers Martin Acevedo, Javier Avalos, and Mario Sanchez (collectively "Defendants"). This matter is before the Court on Plaintiffs' motion to strike Defendants'gang identification expert  and Plaintiffs' to bar Defendants'toxicology expert . For the reasons stated below, Plaintiffs'motion to strike Defendants'gang identification expert is denied and Plaintiffs'motion to bar Defendants' toxicology expert is granted in part.
This case arises out of a May 17, 2005 traffic stop involving Plaintiffs and two Chicago police officers --Defendants Acevedo and Avalos. The facts surrounding that traffic stop are hotly disputed, but the parties agree that there was a physical altercation involving Officers Acevedo and Avalos, Plaintiffs, and a third man, Jose Garcia, after which all five men needed medical attention. It also is undisputed that Plaintiffs were arrested following the confrontation, were charged with multiple counts of felony aggravated battery of a police officer, and were acquitted of all charges following a 2007 criminal trial. In January 2007, Plaintiffs filed the instant civil suit, asserting, inter alia, Section 1983 false imprisonment and excessive force claims.
The parties conflicting accounts of the May 17, 2005 incident are relevant to the Court' s resolution of Plaintiffs' of events.
Plaintiffs contend that they were in a car with a friend, Jose Garcia, on the evening of May 17, 2005, when Rodriguez, the driver, took a wrong turn onto a dead-end street where Defendants Acevedo and Avalos were parked in their squad car. According to Plaintiffs, the officers stopped Plaintiffs'vehicle, exited their vehicle with guns drawn, forcibly removed Plaintiffs from the car, beat them, and placed them under arrest. Plaintiffs characterize this as "a conventional and (unfortunately) common Chicago police 'beat-up case.'"
According to Defendants, it was Plaintiffs and Garcia who instigated the physical confrontation, not the officers. Defendants claim that Officers Acevedo and Avalos were on their lunch break in a dead-end street when they observed Plaintiffs'car speeding, weaving, and entering private property. The officers stopped Plaintiffs, suspecting that the driver was impaired. Defendants maintain that Rodriguez jumped out of his vehicle and attacked Acevedo. While Avalos tried to subdue Rodriguez, Acevedo approached the car and told Garcia to "show me your hands." When Garcia refused, Acevedo pulled him out of the car through the passenger window, and the two began to struggle on the ground. At that point, Martinez got out of the car and jumped Acevedo from behind. Eventually, with the help of additional officers who responded to Defendants'calls for assistance, Rodriguez, Garcia and Martinez were physically subdued and taken into custody.
Therefore, the Court will briefly summarize each side' s version motions.
It is undisputed that Plaintiffs then were taken to the hospital, at which time blood samples were collected from Plaintiff Rodriguez. An analysis of Rodriguez' s blood sample that was taken approximately four hours after the incident with the officers showed a concentration of less than 2.5 micrograms per liter of morphine.
Plaintiffs seek to exclude in its entirety the testimony of Bruce Malkin, a proposed expert witness retained by Defendants in this matter to testify regarding gangs and gang identification. Plaintiffs also seek to exclude certain testimony of Defendant' s proposed toxicology expert, Daniel J. Brown, Ph. D. The Court will address each of Plaintiffs'motions in turn.
II. Motion to Exclude Testimony of Proposed Gang Identification Expert A. Malkin's Opinion Defendants'
proposed gang identification expert, Bruce Malkin, has been a police officer in the City of West Chicago for 30 years, and currently is the deputy chief of patrol operations for the West Chicago Police Department. Between 1997 and 2007, Malkin served as the commander of the West Chicago Police Department' s Street Operations Unit. During that time, his duties included developing gang-related prevention strategies, as well as intelligence gathering and enforcement activities regarding street gangs operating in and around Chicago. Over the past 10 years, Malkin has trained over 1500 police officers about Hispanic street gangs. Malkin also is an active member of the DuPage County State' s Attorney Office "Task Force on Gangs," and has been qualified as an expert witness on street gang identification in the 18th Judicial Circuit of Illinois.
In his expert report, Malkin opines that Plaintiffs are members of a street gang known as the Surenos. Malkin bases that opinion largely on Plaintiffs'tattoos, which he says represent membership in the gang. Malkin also opines that Defendants'account of Plaintiffs'actions on May 17, 2005 --namely, committing an unprovoked attack on police officers -- is consistent with Plaintiffs'gang affiliation. For this opinion, Malkin relies on his law enforcement experience with the Surenos, during which Sureno gang members often would try to fight him, as well as on his general knowledge that gang culture often requires members to participate in illegal activity to achieve gang membership and respect.
Plaintiffs seek to exclude Malkin's proposed testimony on two grounds: (1) Plaintiffs' alleged gang affiliation is not an issue in this case, and therefore Malkin's testimony will not "assist the trier of fact to understand the evidence or to determine a fact in issue," as required by Rule 702 of the Federal Rules of Evidence; and (2) testimony regarding Plaintiffs'alleged gang affiliation should be excluded under Federal Rule of ...