Dog Bite | Animal Behavior Expert Witness

Richard H. Polsky, Ph.D. CDBC
Los Angeles, California

“Bringing the science of animal behavior to attorneys”

Animal behavior expert on dog bite attacks

Richard H. Polsky, Ph.D. CDBC
Los Angeles, California

“Bringing the science of animal behavior to attorneys”

Reconstruction of a German Shepherd attack in a California dog bite lawsuit

Behavioral reconstruction of an incident between German shepherd a UPS driver yielded findings inconsistent with the testimony of the plaintiff.

Reconstruction of a dog bite incident by an animal behavior expert may be beneficial in  lawsuits in which the plaintiff and defense dispute how the incident happened. 

Below, I described a dog bite lawsuit in which the plaintiff, a UPS driver, was attacked by the defendant’s five-year-old German Shepherd, Lucy.

 Did the the plaintiff enter the defendant’s yard in a reckless fashion? This was a question that required expert opinion from a animal behavior perspective. The plaintiff alleged that she took the appropriate actions before entering the defendant’s property in order to deliver the parcel. The defense argued that the plaintiff acted recklessly in a manner that did not ensure her safety.

Below, I summarize my findings and offer animal behavior expert opinion about this incident.

Fact pattern 

The incident happened in the afternoon in residential area in the San Francisco Bay area. The weather was clear and sunny and the ambient noise level in the neighborhood was normal. At the time of the plaintiff’s arrival, the defendant was in her garden approximately 90 feet away from the front gate with Lucy nearby.  The front gate was not visible to the defendant or Lucy from this location. Near the front gate, and clearly visible to visitors who approached the front gate was a “Beware of Dog” sign. The plaintiff denied that she saw this warning sign.

The plaintiff testified that she parked her truck in front of the defendant’s property and approached the closed front gate with the envelope that needed delivery in her hand.  She testified that did not enter the property through the gate at this time. She testified that she heard the defendant talking some distance away. And in order to make her presence known, she shouted “UPS delivery”.  The defendant did not respond,, however. Then according to the plaintiff, she threw the envelope that needed delivery over the gate, but the wind blew the envelope back into her hand.

She then again called out “UPS delivery”, several times and she rattled the gate, and she alleges that she jingled her keys in an attempt to make her presence known.  The defendant did not respond.  The plaintiff then opened the gate and entered the front yard and tossed the envelope on the defendant’s front porch. She turned to exit, but the defendant’s German Shepherd was now in her proximity. Seconds later she was was attacked by Lucy and sustained serious dog bite injury to her left thigh and calf.  The plaintiff heard the commotion and arrived on the scene and pulled Lucy from the plaintiff. The plaintiff testified that approximately 40-60 seconds elapsed from the time when she first made her presence known (that is, by shouting “UPS delivery”, etc.) to when she was bitten.

Argument of the defense

The defense questioned the plaintiff’s version of events, however.  Rather, the defense believed the plaintiff entered the property without properly checking for the presence of a dog.  The defense believed that the plaintiff should have known that a dog was present on the property because of the “Beware of Dog” sign next to the gate.  Moreover, the defense believed that given the strong territorial nature of this German Shepherd, if she had called out “UPS delivery”, rattled the gate and then jingled her keys, then the plaintiff should have been confronted by Lucy shortly thereafter and before she enter the property through the front gate. The defense acknowledged liability, under California’s strict liability for dog bites, but sought to mitigate monetary damages to the plaintiff because of her comparative fault.

Animal behavior reconstruction

Photograph of Lucy at the time of the inspection.

Reconstruction of this dog bite incident involved determining how long it would take Lucy would react to a stranger who made their presence known at the front gate. Specifically, reconstruction sought to determine how long would take Lucy to react to hearing someone calling out “UPS delivery”, rattling the gate, and jingling keys.  How long would it take Lucy to reach the front gate after hearing these stimuli?  Behavioral reconstruction consisted of having the defendant position herself exactly where she was on the day of the incident with Lucy and and re-creating as closely as possible the plaintiff’s actions.

Behavioral testing

Three behavioral tests were conducted. Testing began when Lucy was calm and settled near the defendant in the

Photograph of the front gate.

garden.  Between tests, Lucy was temporarily removed from the garden and brought back several minutes later for the next test. There was a period of about 15 minutes between successive tests. A stopwatch was used to time how long it took Lucy to reach the front gate from her location in the garden.

The first test consisted having the evaluator (this author who serve as the animal behavior expert in this case) next to the front gate and shouting “UPS delivery” approximately 5 times. The second test consisted of having the evaluator rattling the gate for approximately 10-15 seconds. The third test consisted of jingling keys for approximately 10-15 seconds.

These stimuli were specifically chosen because they were the cues that the plaintiff said she used to make the defendant aware of her presence at the front gate.  To reach the gate from the garden, Lucy had to run through bushes on one side of the garden or alternatively move to her right and go and traversed down a cement pathway the front gate.  Each route was approximately 90 feet from the gate.

Results of behavioral testing

The results of the first test, that of the calling out “UPS delivery” were as follows: Lucy immediately barked, and then very quickly she came through the bushes, reached the gate, and started to aggressively bark at the tester. The time it took her to reach the gate from the garden was 13.5 seconds.   

The second test followed approximately 15 minutes later.  The evaluator rattled the gate, and 17.4 seconds later Lucy reached the gate and started barking at the evaluator in an aggressive manner. 

On the third test, the evaluator jingled the keys, and in this instance, Lucy ran to the gate through the bushes. When she reached the gate, she repeatedly barked at the tester in an aggressive manner.  It took Lucy 20.3 seconds to reach the gate. 

Observations of Lucy in the owner’s home

At the conclusion of the third test, the tester entered owner’s home and sat in the living room in the presence of both defendants. Lucy entered the living room, approached the tester in a curious manner to investigate, and then she walked away and settled a short distance away in the hallway.  This was in marked contrast to her aggressive reactivity earlier when she encountered Dr. Polsky ( the tester) at the front gate.

The defendants fully acknowledged that Lucy was protective of her territory, but yet accepting and friendly to people invited into the home. My observations confirm the defendant’s beliefs. Moreover, The defendants noted that Lucy had never bitten a person before the incident with the plaintiff.  They had never received any complaints about Lucy, and they had taken Lucy through obedience school.  It appeared that Lucy was a typical well-bred German Shepherd dog.  Namely, protective of her territory, accepting of strangers invited into the home, and exceptionally loyal to her owners.

Animal behavior expert opinions

The results show faster response times than that alleged by the plaintiff. Lucy’s response time to reach the gate was fastest with the shouting (test one), and faster with the gate rattling compared with the third test, just jingling the keys. Accordingly, jingling the keys resulted in the slowest response time to reach the gate, which was about 20 seconds.

These results show that the the plaintiff’s testimony was inconsistent with the time it should have taken Lucy to reach the front of the house from 90 feet away after she allegedly shouted “UPS delivery”, or rattled the gate, or jingled her keys before opening the gate in entering into the defendant yard to make her delivery. Had the plaintiff taken any of these actions to make her presence known, Lucy should have reached the front of the house much sooner than 40-60 seconds, as alleged by the plaintiff. Rather, behavioral testing showed that if the plaintiff used these stimuli to make her presence known then Lucy should have reached the front gate within 20 seconds, therefore giving plaintiff ample warning about the danger of entering the property to make her delivery.  In sum, the results of the behavioral testing are consistent with the plaintiff opening the gate in entering the yard without taking the steps she alleges to have taken to make her presence known.


Settlement was reached between the parties. The amount of compensation the plaintiff received was lower than what was initially demanded. The settlement amount was not disclosed to Dr. Polsky.


Richard Polsky, Ph.D. is a dog bite expert witness in Los Angeles, California. He welcomes inquiries from attorneys seeking animal behavior expert opinion on German Shepherds.

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