An Review of the San Jose Taser Usage Study

San Jose Police Department's Taser Usage Study: A Case of GIGO

Introduction

San Jose was the first major city in the San Francisco Bay Area to arm all of its patrol officers with Taser electro-shock weapons. On Dec. 3 2004 Rob Davis, Chief of Police, San Jose California released the results of the department's own study of its Taser usage. According to the report of the study:

The study was conducted from May 1, 2004 (the time the majority of the Tasers were issued) until October 31, 2004, a six-month time period.

This is a brief review of the report of that study.

The report of the study is slightly over nine pages in length, and is composed of three sections: “Purpose for the Study”, “Analysis”, and “Conclusion”. This paper reviews each section, and then summarizes. The busy reader can capture the essence by skipping the details, and jumping directly to the summary.

Note: The report uses the term "suspects" (without quotes). I assume what is meant is "persons", but I retained the study's terminology for consistency.

Purpose for the Study

This section of the report establishes the goals of:

• the San Jose Police Department (SJPD)

  ...one of the Department's most important goals is to provide for the safety of the public, the "suspects" who are arrested, and the officers making the arrests.

• San Jose's Taser deployment

  ...Department officials and community leaders...search for additional tools that would allow officers to take combative "suspects" into custody using the least amount of force necessary to make the arrests safely and effectively.

  ...The Taser...gives patrol officers another tool when dealing with persons who are physically threatening, assaultive, attempting to flee a detention or arrest, or are resistive or physically uncooperative.

• The Taser Usage Study

  Tasers...studied to determine if they were being deployed effectively and to identify any training issues that might arise.

  This reveals a crucial and fundamental flaw of the study: it is not concerned with the safety of Taser deployment. Although safety is mentioned as the most important goal of SJPD, and the stated purpose of Taser deployment is to make the arrest both safely and effectively, the stated purpose of the study is only to determine if Tasers were being deployed "effectively" (i.e., "safely", not mentioned). The safety of Taser deployment is one of the two top concerns of the community. The other concern is the circumstances under which Tasers are deployed: do they really reduce the force used, or are they being deployed in circumstances where force would not normally be used?

This section of the report also establishes the metrics used for the study:

• the number of times Tasers were deployed

• the manner in which the Tasers were deployed

• the number of calls to which officers were dispatched and a Taser was deployed

• the number of times officers deployed a Taser during a self-initiated activity

• the race/ethnicity of the “suspects” upon whom the Taser was deployed, compared with the arrest rates for all “suspects” arrested or cited for a criminal offense during the same time period

• the overall number of calls for service handled by patrol officers during the period of study

• the gender of the “suspects” involved

• the number of adults and juvenile “suspects” involved

• the number of “suspects” involved believed to be under the influence of drugs and/or alcohol

• the number of “suspects” involved believed to be suffering from mental illness (as identified either before or after the event)

• the number of “suspects” involved believed to be suffering from mental illness and who were believed to be under the influence of drugs and/or alcohol

• the number of officer injuries sustained when making arrests compared to the same time period in the previous year

Note that none of the above metrics used by the study measure the effectiveness of Taser deployment, as defined by the purpose of deployment: to use

...the least amount of force necessary to make the arrests safely and effectively

The metrics used do not help us determine if the least amount of force was used during Taser deployment. Some metrics to measure amount of force used during Taser deployment include:

• Number of cases where other types of force or compliance techniques were used before Taser was deployed, and descriptions of the force or technique

• Number of cases where other types of force or compliance techniques were used after Taser was deployed, and descriptions of the force or technique

• Total number and type of use-of-force incidents (compared to the same time period in previous years), to determine if Tasers affect overall use of force. That is, did the Taser usage really replace other force or just add to it?

• Frequency distribution of shocks to "suspects" (Number of "suspects" receiving 1 shock, number receiving 2 shocks, and so on)

Also, the report implies that each use of Taser was followed by arrest. But the incidence of arrest after Taser usage needs to be made explicit, since it is an important factor to consider when determining if appropriate force was used. We need to know what was the initial description and final charge (if any) for each of the 110 cases.

Given that the report states that:

...one of the Department's most important goals is to provide for the safety of the public, the "suspects" who are arrested, and the officers making the arrests.

one would expect to the study to include:

• Number and severity of injuries sustained by public when making arrests (compared to the same time period in previous years).

• Number and severity of "suspect" injuries sustained when making arrests (compared to the same time period in previous years).

• Number and severity of officer injuries sustained when making arrests (compared to the same time period in previous years).

The severity can be given by describing the injury and medical attention required.

The report provides only part of the last metric (compared only to last year; severity of injury not reported). It is quite revealing that the safety of the public or "suspects" was not a concern of the study.

Analysis

Circumstances Surrounding Taser Deployment

Given the stated rationale for Taser deployment:

...The Taser...gives patrol officers another tool when dealing with persons who are physically threatening, assaultive, attempting to flee a detention or arrest, or are resistive or physically uncooperative.

One would expect to see a breakdown according to type of circumstance:

• Number of "suspects" shocked for being physically threatening

• Number of "suspects" shocked for being assaultive

• Number of "suspects" shocked for fleeing

• Number of "suspects" shocked for being resistive or physically uncooperative

Also, it would be useful to include:

• Number of unarmed "suspects" shocked

None of these were provided. So the report leaves unanswered the basic question being raised by the community: do Tasers really reduce the force used, or are they being deployed in circumstances where force would not normally be used?

The information that is included is of questionable value. It is not clear that the data about what the officer "believed" about the "suspect's" mental state or sobriety is meaningful. For example, LAPD officers "believed" Glen “Rodney” King was drugged on PCP, but that turned out to be false.

Another item of limited use is the list of initial descriptions of the events officers either responded to or initiated during Taser deployments. Initial descriptions don't provide actual type of circumstance, as given in the above rationale for Taser deployment. They also are not reliable indicators of the presence of weapons. For example, a call initially described as Domestic Violence may or may not have involved a weapon. Looking at the initial descriptions of the Taser deployment, the "Disturbance Call" is highest (30), more than the next two descriptions combined: Person Under the Influence of Controlled Substances (16), Mentally Disturbed Person Calls (13). The next most frequent description is Trespassing (6). Together these four descriptions cover 65 of the total 110 Taser deployments, or 59%. Only 7 Taser deployments (6%) were on calls that explicitly mention a weapon: Assault With A Deadly Weapon (2), Brandishing a Weapon (4), Driving Under the Influence and Brandishing a Weapon (1). Superficially, it would seem that Tasers are mostly being deployed in circumstances that mental health professionals and others routinely deal with without any weapons. But, again, initial descriptions are not reliable enough to make that claim with a sufficient degree of certainty.

Race/Ethnicity of "Suspects" Compared to Overall Arrest Rate was added to report in response to a request by Rick Callender, president of the San Jose/Silicon Valley chapter of the NAACP. For the purposes of this review, ethnic data is irrelevant to the central issues of safety and escalation of force.

Injuries Sustained By Officers as a result of an altercation dropped to 20, compared to 25 in the same period of the previous year. There's no way to determine from this if this drop is significant: the number of officer injuries may normally fluctuate over the years. And even if we could determine its significance, the data does not establish any causal link to Taser deployment. The drop could be due to other factors.

Examples of Taser Usage

Officers were able to gain compliance merely by pointing the Taser at the "suspect" and advising the “suspect” they would deploy it if he did not cooperate.

This example is not within the stated scope of the study: actual Taser deployment. The study states that Taser usage was tracked under three categories, depending on the way the Taser was used: in "Air Tase" mode (using darts - 70 cases), "Drive Stun" mode (placed directly to body - 25 cases), or using both modes (15 cases). That totals to 110 cases. So what category does this "typical" example fall under? This inconsistency casts a doubt on the integrity of the entire data set. I've left a voicemail query with Lt. Gary Kirby of the San Jose Police Department's Research and Development Unit, and I'm still waiting for a reply.

Another of the "typical" examples presented a different difficulty: I could not visualize the described event:

An officer observed a "suspect" urinating in public. When he confronted the "suspect", the "suspect" swore at the officer and lunged at him with a bottle.

In the first sentence, the "suspect" is exposing himself and, presumably, at least one of his hands is occupied by something not very useful as a weapon against police. By the second sentence, he is lunging at the police with a bottle. I stretched my imagination as far as I could, but I simply could not connect those two images without inserting intermediate events. If those intermediate events occurred, but are not reported, then this "typical" example is useless without a description of the "suspect's" and officer's actions during those intermediate events.

Since I have unresolved questions about 25% of the examples given, I am deferring review of the remaining examples until my questions regarding the integrity of the data are resolved.

Conclusion

• As mentioned above, the ethnic data was an add-on that is irrelevant to the central issues of safety and escalation of force. Consequently, although the ethnic data was the main focus of press reports, this review ignores the irrelevant conclusions drawn on that irrelevant data.

• The report concludes:

  ...the Taser device clearly enabled San Jose Police Officers to use lower levels of force to gain compliance from combative and dangerous suspects in a substantial percentage of cases in this study.

  This is not at all clear, since no data is given to support this conclusion. What is the "substantial percentage"? How does the study define "lower levels of force"? For example, some departments place pepper spray as lower force than Tasers, while others place it on the same level.

• The report also concludes:

  The study also tends to indicate that fewer officers suffered injuries due to altercations with "suspects" when officer had access to Tasers.

  As mentioned above, the data does not support this conclusion since there is no evidence given to show that the drop in injuries is significant, and not merely normal fluctuation. Moreover, no evidence is given to support the conclusion that the drop is linked to Taser deployment.

Summary

The report is fatally flawed by:

• Metrics that not only do not reflect the needs and interests of the community, but do not even reflect either the stated goal of the San Jose police department, or the stated rationale for arming patrol officers with Tasers. The metrics do not address the safety of the public or of persons taken in custody when Tasers are deployed. The metrics also do not address the key question of Taser usage: do they really reduce the force used, or are they being deployed in circumstances where force would not normally be used? These are top concerns of the community, but the report ignores these concerns.

• An example of Taser deployment (one of only eight) where the Taser is not actually deployed: compliance is gained merely by pointing the Taser. The report claims the examples are typical, yet this example falls outside the stated scope of the study: actual Taser usage. This inconsistency casts a doubt on the integrity of the entire data set.

• Conclusion drawn from insufficient data. Conclusions can't be drawn by merely comparing data before and after Tasers. We must compare the data after Taser with data that has been established as the norm. Otherwise, we don't know whether or not any change is significant, or merely just random fluctuation. The conclusion must also establish a causal link to Tasers for any change deemed significant.

From the report it seems that the study is merely yet another case of GIGO: Garbage In, Garbage Out. Though the release of the report received much press attention, one wonders how much attention was given to the actual content of the report. The report only serves to pollute the Taser debate with data that is (at best) irrelevant, and sometimes even questionable.

American Dream, 0506 19 Dec 2004