Terence Tribble v. Nicholas Evangel, 670 F.3d 753

Tribble was arrested on Mother's Day 2006 for drinking on a public way; search incident to arrest yielded heroin and crack, leading to drug charges.
Cook County judge at a preliminary hearing found no probable cause for the drug charges; the case was dismissed on that basis.
Tribble filed a 42 U.S.C. § 1983 suit alleging illegal stop, false arrest, illegal search, and due process violations.
The district court pretrial ruled against admitting testimony that would explain the state court’s no-probable-cause finding, barring such testimony.
Defendants substituted Assistant State's Attorney Ebersole for Sleesman a week before trial; the court allowed the substitution, despite claims of potential prejudice.
Ebersole testified (as an undisclosed expert) about Branch 50’s handling of low-weight narcotics cases and the prevalence of no-probable-cause findings, influencing the jury’s view of Tribble’s case.

Issue	Plaintiff's Argument	Defendant's Argument	Held
Whether Ebersole's testimony was proper expert testimony	Tribble argues Ebersole testified as an expert and required disclosure.	Defendants contend testimony derived from her role as an experienced witness, not an expert.	Ebersole testified as an expert and required disclosure.
Whether failure to disclose Ebersole as an expert was harmless	Non-disclosure prejudiced Tribble by precluding rebuttal and limiting defense strategy.	Non-disclosure was not harmless due to potential impact on trial strategy.	Non-disclosure was not harmless; exclusion for non-disclosed expert was mandatory.
Whether the district court erred in allowing the expert testimony despite a pretrial ruling	District court should have adhered to the ruling prohibiting testimony about Branch 50’s general practices.	Swapping Sleesman for Ebersole and allowing testimony aligned with defense theory and evidence available.	District court erred by allowing undisclosed expert testimony contrary to its pretrial ruling.
Whether Tribble should be allowed to amend to add a Fourth Amendment strip-search claim	Amendment should be freely granted to address new jurist-appropriate issues.	Late amendment would prejudice defendants and is futile.	District court’s denial of leave to amend was affirmed; strip-search claim not added.

United States v. Conn., 297 F.3d 548 (7th Cir. 2002) (distinguishes expert vs. lay testimony for Rule 702)
Echo Inc. v. Timberland Machines & Irrigation, 661 F.3d 959 (7th Cir. 2011) (categorization of testimony as expert or lay reviewed de novo)
Beech Aircraft Corp. v. Rainey, 488 U.S. 153 (U.S. 1988) (Bech/Beek: distinction between lay and expert testimony (Rule 701/702))
Musser v. Gentiva Health Serv's, 356 F.3d 751 (7th Cir. 2004) (automatic exclusion for non-disclosed experts under Rule 37)
David v. Caterpillar, Inc., 324 F.3d 851 (7th Cir. 2003) (factors for harmlessness of Rule 26(a) violations)
Grove Fresh v. New England Apple Prod., 969 F.2d 552 (7th Cir. 1992) (pretrial rulings on witness substitution and impact on trial)