Opinion ID: 579428
Heading Depth: 2
Heading Rank: 2

Heading: The Limits on Cross Examination

Text: 27 Montague further urges that the District Court erred in limiting his cross examination of Detective Lawrence Coates, the government's expert witness. The court had accepted the qualification of Coates as expert in the area of the use, packaging, and distribution of narcotics, and police procedures for handling narcotics. The defense attempted to cross examine Coates on the effect of crack cocaine on the user's memory and abilities of observation, apparently in an attempt to impeach the testimony of Rustin and another government witness. The government argued and the District Court ruled that Coates was not qualified to deliver medical opinions. 28 The subject of expert testimony under the Federal Rules of Evidence is governed by Rules 702-706. Rule 702 states: 29 If scientific, technical, or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training, or education, may testify thereto in the form of an opinion or otherwise. 30 The scope of the witness's field of expertise is largely committed to the discretion of the trial court. United States v. Carswell, 922 F.2d 876, 878 (D.C.Cir.1991) (citation omitted). Where the cross examiner attempts to go far beyond the subject matter of the direct, we are not likely to find that the trial judge abused that discretion by imposing limits related to the scope of the direct examination. We do not so find here. 31 [294 U.S.App.D.C. 242] Indeed, even were we not dealing with a subject as plain as the difference in expertise between the packaging of drug materials and the medical effects of the drugs, the general rule of competency of Federal Rule of Evidence 611(b) limits cross examination to the subject matter of the direct examination and matters affecting the credibility of the witness. Here the limits placed by the judge are totally consistent with that Rule.