128 F.4th 1319
10th Cir.2025Background
- Amelia Baca, a 75-year-old woman with dementia, was fatally shot by Officer Jared Cosper in her home in Las Cruces, New Mexico, after a 911 call reporting her threatening her family with knives.
- Baca was holding two knives when Officer Cosper arrived; she did not appear to make aggressive movements, charge, or attempt to stab or slice at officers.
- Officer Cosper shot Baca within 45 seconds of arriving, after she made two slow steps toward him; she remained with knives pointed to the ground and made no stabbing gestures.
- Ms. Baca's estate sued Officer Cosper under 42 U.S.C. § 1983, alleging excessive force in violation of the Fourth Amendment.
- The district court granted Officer Cosper summary judgment based on qualified immunity, concluding no triable dispute about whether he perceived an immediate threat.
- On appeal, the Tenth Circuit reversed the summary judgment, holding a reasonable jury could find Baca did not pose an immediate threat and that legal standards were clearly established by prior circuit law.
Issues
| Issue | Plaintiff's Argument | Defendant's Argument | Held |
|---|---|---|---|
| Excessive Force (4th Amendment) | Baca posed no immediate threat; no aggressive knife motion | Cosper believed she was an immediate threat | Jury could find excessive force occurred; summary judgment reversed |
| Qualified Immunity | Law was clearly established against such use of deadly force | Officer's actions reasonable under threat perception | Clearly established law existed; summary judgment reversed |
| Objective Reasonableness of Force | No charge/stabbing motion; knives pointed down | Stepping forward was a hostile motion; threat to others | Reasonable officer could view conduct as non-hostile |
| Availability of Safer Alternatives | Cosper could have retreated; backup available | Retreat posed risk to others; retreat not feasible | Cosper not unreasonably confined; alternatives existed |
Key Cases Cited
- Graham v. Connor, 490 U.S. 386 (U.S. 1989) (establishes objective reasonableness test for use of force under the Fourth Amendment)
- Scott v. Harris, 550 U.S. 372 (U.S. 2007) (bodycam evidence governs factual disputes at summary judgment)
- Mullenix v. Luna, 577 U.S. 7 (U.S. 2015) (clearly established law must be particularized to facts)
- Walker v. City of Orem, 451 F.3d 1139 (10th Cir. 2006) (deadly force unreasonable where knife not raised against officer)
- Zuchel v. City & Cnty. of Denver, 997 F.2d 730 (10th Cir. 1993) (deadly force not justified when suspect with knife does not pose immediate threat)
- Estate of Larsen ex rel. Sturdivan v. Murr, 511 F.3d 1255 (10th Cir. 2008) (factors for assessing reasonableness of deadly force)
- Tenorio v. Pitzer, 802 F.3d 1160 (10th Cir. 2015) (deadly force against non-charging, non-aggressive knife holder violates clearly established law)