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Federal Appellate Court Reverses lower court and rejects Dallas officers’ qualified immunity defense

Court rules that jury could find officer’s application of a knee to a mentally ill subject’s back beyond that necessary to control him


On August 10, 2016, Anthony Timpa called 911, provided his location and requested help. He said he had a history of mental illness, was off his medications and was very anxious. Another caller from the same location reported that a man was running up and down the street, stopping traffic and attempting to climb a public bus. The dispatcher informed responding Dallas Police Department (DPD) officers that they were being directed to a Crisis Intervention Training (CIT) situation involving a mentally ill person.

Sergeant Mansell, Dallas Police Department arrived first and found Timpa had already been handcuffed by two private security guards. He was sitting barefoot on grass near the sidewalk. Timpa began thrashing around and kicking his legs in the air. He hollered, “Help me, … God help me.” Timpa rolled himself into the gutter of the nearby street, causing Mansell and a security guard to move him back on the grass. Mansell requested assistance and an ambulance.

DPD officers Dillard, Vasquez, Rivera and Dominguez arrived on scene, along with two paramedics. Three of the officers wore body cameras, which captured the next several minutes of the incident. Timpa was lying on his back, rolling back and forth on the grass and yelling, “Help … You’re gonna kill me.” After he rolled close to the street, Dillard and Vasquez forced Timpa onto his stomach and each pressed a knee onto his back while a security guard restrained his legs. Vasquez removed his knee after approximately two minutes. However, Dillard pressed his knee into Timpa’s back in the prone restraint position for a total of 14 minutes and seven seconds.

During the first seven minutes of Timpa’s restraint by Dillard, he continued to flail around and struggle. He also admitted having taken cocaine and was exhibiting signs of excited delirium. [1]

During this period, officers were able, with some difficulty, to exchange the handcuffs on Timpa with police handcuffs and zip-tie his ankles. At the nine-minute mark of Dillard’s knee on Timpa’s back, Timpa’s legs stopped kicking. Shortly after the 10-minute mark, Timpa stopped crying out and was quiet except for a few moans. He fell limp and was nonresponsive for the final three and a half minutes of the knee restraint. The paramedics determined that Timpa was dead.

The Dallas County medical examiner conducted Timpa’s autopsy and ruled the death a homicide. The medical examiner found cocaine in Timpa’s system and concluded he was suffering from “excited delirium.” His report stated that Timpa died from “sudden cardiac death due to the toxic effects of cocaine and [the] physiologic stress associated with physical restraint, which could have resulted in mechanical or positional asphyxia.”

The lawsuit

Timpa’s family sued the DPD officers in federal court pursuant to the federal civil rights statute, 42 U.S.C. § 1983. The lawsuit alleged use of excessive force against Dillard and bystander liability against the remaining officers.

The Federal District Court dismissed the lawsuit against all defendant officers on qualified immunity grounds. The court ruled that “there was no law clearly establishing Defendants’ conduct as a constitutional violation prior to August 10, 2016.”

The family filed an appeal with the United States Court of Appeal for the Fifth Circuit. The Fifth Circuit reversed.

Fifth Circuit decision [2]

The Court of Appeals began by explaining the plaintiff’s burden to overcome an officer’s assertion of qualified immunity. The court stated, “Thus, to defeat a motion for summary judgment based on qualified immunity, the plaintiff must present evidence ‘(1) that the official violated a statutory or constitutional right, and (2) that the right was ‘clearly established’ at the time of the challenged conduct.’” [3]

The Graham factors

Plaintiff alleged that Dillard violated a constitutional right (i.e., the Fourth Amendment) by using excessive deadly force. The court observed that the “reasonableness of the use of force turns … particularly [on] the following three factors: (1) ‘the severity of the crime at issue,’ (2) ‘whether the suspect pose[d] an immediate threat to the safety of the officers or others,’ and (3) ‘whether he [was] actively resisting arrest or attempting to evade arrest by flight.’” Graham v. Connor, 490 U.S. 386, 396 (1989).

The court quickly dismissed the first “Graham” factor by observing that officers were not confronted with serious criminal activity in dealing with Timpa. Instead, they were called by Timpa himself to help him deal with a mental health crisis.

The court next applied the second “Graham” factor (i.e., the immediacy of the threat) and observed, “Approximately nine minutes into the restraint, Timpa was cuffed at both the wrists and the ankles, his lower legs had stopped moving, and he was surrounded by five officers, two paramedics, and two private security guards —… while Dillard maintained his bodyweight force on Timpa’s upper back. As to any threat of harm to the Officers, it is obvious that Timpa could no longer kick when he was lying face down and handcuffed with his ankles restrained.”

The court examined the third “Graham” factor regarding active resistance. The court observed that during the initial moments of the encounter and beyond, Timpa was struggling with the officers and flailing about. However, the court explained, “even assuming that Timpa’s flailing amounted to active resistance, ‘the force calculus change[d] substantially once that resistance end[ed]’ nine minutes into the restraint.’” [4]

Officer training on positional asphyxia

The court noted that Dillard had been trained in the use of a prone restraint to control subjects in a state of excited delirium. The training included a warning that persons with excited delirium must as soon as possible be moved to an upright seated position or on their side to prevent positional asphyxia death. Dillard was also trained that “[i]f [the] subject suddenly calms, goes unconscious, or otherwise becomes unresponsive, . . . [a] sudden cessation of struggle is a prime indicator that the subject may be experiencing fatal autonomic dysfunction (sudden death).” [5]

The court concluded by rejecting Dillard’s qualified immunity claim and explained, “none of the Graham factors justified the prolonged use of force. A jury could find that Timpa was subdued by nine minutes into the restraint and that the continued use of force was objectively unreasonable in violation of Timpa’s Fourth Amendment rights.” The court explained further, “Here, a prone restraint was used in tandem with Dillard’s body weight for over fourteen minutes. If a jury were to find that Timpa was subdued and nonthreatening by nine minutes into the restraint, then the continued use of force for five additional minutes was necessarily excessive.”

Clearly established law violated

The court examined prior Fifth Circuit case law and similar cases decided in other federal circuits and observed, “These cases clearly established the unreasonableness of Dillard’s continued use of bodyweight force to hold Timpa in the prone restraint position after he was subdued and restrained.” [6]

Bystander liability

The court likewise rejected qualified immunity assertions from officers Vasquez and Dominguez. The court observed that both officers stood close by throughout the 14-minute restraint applied to Timpa by Dillard. Both failed to intervene even though they were trained that once a resisting subject is under control, they must be placed upright or on their side. The court stated, “both officers ‘stood by and laughed’ while Dillard continued to kneel on an incapacitated arrestee [and this] supports an inference of ‘acquiescence in the alleged [improper] use of force.’”

The court also rejected Sgt. Mansell’s qualified immunity claim. He was present during the incident, including the “critical half-minute when Timpa suddenly lost consciousness. Moreover, the record supports an inference that Mansell was aware Timpa had become incapacitated.” The court dismissed the fact that “thirty-four seconds after Timpa became subdued, he returned to his patrol car ‘a few feet away’ and sat ‘with the door open’ while he ran a check on Timpa’s license.” The court ruled that a jury could find that Mansell should have intervened and failed to do so. [7]

Lessons learned

  • Officers must be extremely careful in applying body pressure, including knee pressure, to the chest or upper back of a resisting subject. If applying body pressure is deemed necessary to control a subject, the subject should be raised to a sitting position or placed on their side as soon as possible. Failure to do this may result in positional asphyxia and death.
  • Officers accused of causing death by positional asphyxia in criminal or civil litigation are likely to have their training on this issue used against them in court proceedings.
  • Officers, like those involved in the instant matter, are also likely to have other well-documented publications used against them in subsequent litigation, e.g. the U.S. Department of Justice Treatise on the dangers involved in using restraint pressure resulting in positional asphyxia and sudden death. See, Nat’l Law Enf’t Tech. Ctr., U.S. Dep’t of Just., Positional Ashyxia—Sudden Death (1995).
  • The defendant officers in the instant matter also had Dallas police regulations entered against them during court proceedings. The regulations required officers to place resisting subjects in an upright position or on their side as soon as they are brought under control.
  • Officers should never joke about the condition of an injured subject because they are likely to find that their in-jest comments caught by camera as in the instant matter and will be used against them in court.
  • This case went to trial in September 2023. A federal jury ruled that Dillard, Dominguez and Vasquez violated Timpa’s Fourth Amendment rights but gave Dillard and Vasquez qualified immunity. Sgt. Mansell was vindicated entirely, and the City of Dallas was ordered to pay damages in the amount of $1 million. See, Billy Binion, “Tony Timpa … Trial Ends With 2 Out of 3 Cops Getting Qualified Immunity,” Reason Magazine, 9/27/2023.


1. According to the court, excited delirium involves a “state of agitation, excitability, and paranoia … often associated with drug use, most commonly cocaine’”’ Goode v. Baggett, 811 F. App’x 227, 233 n.6 (5th Cir. 2020} (citing, Gutierrez v. City of San Antonio, 139 F.3d 441, 444 (5th Cir. 1998).
2. Timpa v. Dillard, 20 F.4th 1020 (5th Cir. 2021).
3. Morgan v. Swanson, 659 F.3d 359, 371 (5th Cir. 2011) (en banc) (quoting Ashcroft v. al-Kidd, 563 U.S. 731, 735 (2011)). III.
4. (Quoting, Curran v. Aleshire, 800 F.3d 656, 661 (5th Cir. 2015)).
5. The court also stated in footnote 3 of the opinion, “A jury could also consider prominent guidance circulated by the Department of Justice warning of the risk of positional asphyxia resulting from the use of a prone restraint. See Nat’l Law Enf’t Tech. Ctr., U.S. Dep’t of Just., Positional Ashyxia—Sudden Death (1995); cf. Lombardo, 141 S. Ct. at 2241 (noting that ‘well-known police guidance; warning ‘that the struggles of a prone suspect may be due to oxygen deficiency, rather than a desire to disobey officers’ commands,’ reflects on whether the force used was excessive).”
6. See, e.g., Darden v. City of Fort Worth, 880 F.3d 722 (5th Cir. 2018); McCue v. City of Bangor, 838 F.3d 55, 64 (1st. Cir. 2016); Weigel v. Broad, 544 F.3d 1143, 1155 (10th Cir. 2008); Abdullahi v. City of Madison, 423 F.3d 763, 764-766 (7th Cir. 2005).
7. With regard to officer Rivera, the court determined that he was entitled to qualified immunity because he lacked a reasonable opportunity to intervene.

Readers respond

I enjoyed reading Mike Callahan’s excellent legal analysis of the Timpa v. Dallas case in his Jan 2 article. I was a defense scientific expert in that trial and had the privilege of working with the Dallas City trial lawyer, Lindsay Gowin.

My only quibble with the article is that some of the “lessons learned” might be confusing the legal landscape with scientific reality. For example, there are indeed case law, regulations and police advisory group rules against prone restraint and warnings about so-called “positional asphyxiation.” Those are based on the popular media myth that the prone position interferes with breathing and gas exchange. [1,2] However, scattered papers have long reported improved gas exchange with the prone position. [3-10] This suddenly became an urgent matter with COVID and we now have multiple studies showing better gas exchange in the prone position. [11-15] Even the New York Times recognized this in 2020.

There is a natural intuition to consider a seated position as somehow healthy and normal. In fact, the worst position for breathing — especially with a subject carrying extra abdominal weight — is a sitting position on the ground. The abdomen is pinched and this interferes with diaphragmatic breathing. [16] The side positions have several detrimental effects and should generally be avoided except for someone who has vomited.

A full discussion of the ground restraint issues goes well beyond the scope of this letter so the reader is invited to read the online article.

This letter is not meant to make light of the legal predicament that officers are found in. The violent restrained subject has the best chance of survival if kept in a prone position. On the other hand, if this subject ends up dying then the police officer may face criminal charges for going against the conventional wisdom regarding the mythical “positional asphyxia.” Therefore, a cold calculating officer may choose to put the subject in a left-lateral or seated position even when they know that that is physiologically harmful. While it is harmful to the subject, it is legally protective for the officer.

— Mark Kroll, Ph.D., FAIMBE, FACC


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3. Sud S, Friedrich JO, Taccone P, et al. Prone ventilation reduces mortality in patients with acute respiratory failure and severe hypoxemia: systematic review and meta-analysis. Intensive Care Med. 2010;36(4):585-599. doi:10.1007/s00134-009-1748-1.
4. Alsaghir AH, Martin CM. Effect of prone positioning in patients with acute respiratory distress syndrome: a meta-analysis. Crit Care Med. 2008;36(2):603-609. doi:10.1097/01.CCM.0000299739.98236.05.
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8. Mure M, Glenny RW, Domino KB, Hlastala MP. Pulmonary gas exchange improves in the prone position with abdominal distension. Am J Respir Crit Care Med. 1998;157(6 Pt 1):1785-1790. doi:10.1164/ajrccm.157.6.9711104.
9. Mure M, Martling CR, Lindahl SG. Dramatic effect on oxygenation in patients with severe acute lung insufficiency treated in the prone position. Crit Care Med. 1997;25(9):1539-1544. [Accessed]. Available from:
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11. Cohen D, Manuel J, Timsit JF, et al. Beneficial effect of awake prone position in hypoxaemic patients with COVID-19: case reports and literature review. Intern Med J. 2020;50(8):997-1000. doi:10.1111/imj.14926.
12. Padrao EMH, Valente FS, Besen BAMP, et al. Awake Prone Positioning in COVID-19 Hypoxemic Respiratory Failure: Exploratory Findings in a Single-center Retrospective Cohort Study. Acad Emerg Med. 2020;27(12):1249-1259. doi:10.1111/acem.14160.
13. Gupta S, Govil D. Prone for COVID: Are You Awake? Indian J Crit Care Med. 2020;24(7):504-505. doi:10.5005/jp-journals-10071-23497.
14. Singh P, Jain P, Deewan H. Awake Prone Positioning in COVID-19 Patients. Indian J Crit Care Med. 2020;24(10):914-918. doi:10.5005/jp-journals-10071-23546.
15. Sztajnbok J, Rosa RG, Thomé AMC, et al. Prone positioning to improve oxygenation and relieve respiratory symptoms in awake, spontaneously breathing non-intubated patients with COVID-19

John Michael Callahan served in law enforcement for 44 years. His career began as a special agent with NCIS. He became an FBI agent and served in the FBI for 30 years, retiring in the position of supervisory special agent/chief division counsel. He taught criminal law/procedure at the FBI Academy. After the FBI, he served as a Massachusetts Deputy Inspector General and is currently a deputy sheriff for Plymouth County, Massachusetts. He is the author of two published books on deadly force and an upcoming book on supervisory and municipal liability in law enforcement.

Contact Mike Callahan.