Expert litigation terms,
defined for counsel.

The attorney or firm that engages the expert and sets the scope of the work. The retention runs to counsel and counsel’s staff, never to an individual party: the expert is not an attorney, gives no legal advice and makes no attorney referrals. Retaining counsel frames the questions, assembles and ships the record, controls disclosure, and remains responsible for the admissibility of the report and the testimony.

An expert designated to give opinions that are disclosed to the opposing parties, subject to deposition and examination at trial. Designation changes how the file is handled: the facts and data considered, the compensation, and the assumptions counsel supplied are all fair territory on cross. Fed. R. Civ. P. 26(b)(4) shields draft reports and most attorney-expert communications, with stated exceptions, but the working assumption is that the finished analysis must stand on its own.

An expert retained to advise counsel without being disclosed as a witness. Consulting-only engagements support merit evaluation, discovery planning, questions for the depositions of officers and opposing experts, and settlement or mediation strategy. The work generally stays behind the disclosure line unless the expert is later designated. Counsel who may want that option should scope the engagement for it at retention, because the decision changes how the file is built.

The protection that shields materials prepared by or for counsel in anticipation of litigation from ordinary discovery. Its most cited application in expert practice is Fed. R. Civ. P. 26(b)(4), which protects draft expert reports and most communications between counsel and a testifying expert, subject to exceptions for compensation, for facts or data counsel supplied, and for assumptions counsel asked the expert to adopt. How the doctrine applies in a given matter is counsel’s call.

The federal rule governing expert testimony: the witness must be qualified, the testimony must help the trier of fact, it must rest on sufficient facts or data and on reliable principles and methods, and those must be reliably applied to the facts of the case. Police practices testimony is experience-based, and Kumho Tire Co. v. Carmichael, 526 U.S. 137 (1999) extends the reliability inquiry past scientific testimony to technical and other specialized knowledge.

A motion asking the court to limit or exclude expert testimony under Fed. R. Evid. 702 and the reliability standard of Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993). The label travels to state court, but state courts set their own admissibility tests, some tracking the federal rule and others retaining a general acceptance standard, so the test that governs is the one the forum applies. In police practices matters the recurring attacks are that the opinion states a legal conclusion, that the standard invoked is not generally accepted, or that the expert reviewed too little of the record. Each is answered on the paper.

Examination of an expert’s qualifications before the testimony is received, conducted by opposing counsel and sometimes by the court. It is short, it is about foundation rather than opinion, and it comes before any ruling on whether the witness may testify as an expert. Preparation for it is documentary: a current curriculum vitae, an accurate list of prior testimony, and a clean account of the experience supporting each opinion offered.

The question the trier of fact must decide, such as whether a defendant is liable or guilty. A police practices expert measures conduct against generally accepted practices, agency policy and national standards; the expert does not tell the jury who should win. Reports state in writing that the opinions address police practices and that legal conclusions remain counsel’s and the court’s, which is also the cleanest answer to a motion arguing the expert invaded the jury’s function.