Canadian authorities are being warned about a controversial U.S.-based "police psychologist" who critics say provides advocacy testimony for officers accused of wrongful shootings.

Bill Lewinski, a self-proclaimed authority in police use of force, has testified as an expert exclusively for police officers in as many as 75 cases in the United States since 1990.

More recently, he has testified in at least three cases in Canada, including two in Alberta.

He has also conducted use-of-force training for police officers from Edmonton and Calgary.

But American critics question Lewinski’s credentials, his research and his testimony.

They say Lewinski is a "professional witness" who will change his testimony, even contradicting his own "pseudo-scientific" research, to try to help exonerate police officers accused of wrongful shootings.

"He will reverse-engineer from his conclusion, which is that the shooting was justified, to explain away whatever physical evidence doesn’t fit that conclusion," said John Burton, a Pasadena, Calif. civil-rights lawyer who specializes in wrongful police shootings and has twice cross-examined Lewinski.

Lewinski, who was born in Canada, declined several interview requests. But in an email, he defended his academic reputation, his research and his testimony.

He said his Minnesota-based organization, Force Science Institute, has made numerous presentations to the International Associations of Chiefs of Police.

The institute, he said, is also working with the University of Portsmouth in England and the University of California Los Angeles.

"Further, I am a peer reviewer for five journals," Lewinski wrote. "How could I do this and be invited to do two presentations to Parliament in the UK to subcommittees from the House of Commons and House of Lords if our research wasn’t credible?"

Testified in controversial cases in Alberta and B.C.

Lewinski is now exporting his controversial theories about police shootings to Canada.

Last year, his testimony played a major role in the decision by in an internal disciplinary hearing to clear Edmonton Police Service officer Bruce Edwards of allegations of excessive force.

Court of Queen’s Bench Justice Eric Macklin had previously ruled Edwards committed an "unconscionable use of excessive and aggressive force" when he shot Kirk Steele four times in July 2006, after he saw Steele stab his police dog.

But the presiding officer in the subsequent internal police disciplinary hearing pointedly rejected the judge’s finding. Retired Calgary police Insp. Paul Manuel cited extensively from the testimony of Lewinski.

"Had Justice Macklin been afforded the expert opinion of Dr. Lewinski" and another psychologist, Manuel wrote, "he may not have made these statements."

Steele has appealed Manuel’s ruling the provincial Law Enforcement Review Board (LERB). His lawyer, Tom Engel, said Lewinski should never have been called as a witness.

"He never testifies for anyone other than the police," Engel said. "So that suggests bias.

"He’s very well known in police circles in North America now as being the type of guy who you can go to, in a case like this, and get an opinion favouring the police," Engel said, adding that he will ask the LERB to exclude Lewinski’s evidence because it is biased.

Vancouver officer shot unarmed man

Lewinski’s testimony also played a significant role in a decision to exonerate a Vancouver police officer in a controversial, high-profile shooting.

Const. Lee Chipperfield shot Paul Boyd eight times following an altercation with police in 2007. But it was a final shot to the head while Boyd was on the ground and disarmed that killed the mentally ill man.

Stan Lowe, the province’s police complaints commissioner, hired Lewinski and relied heavily on his expert opinion in his final report.

Lowe wrote Lewinski had "reasonably explained" that Chipperfield had fired on an unarmed man due to the "intense emotional reaction to the events, coupled with a restricted focus," which had "rendered him inattentionally blind."

Although Chipperfield and Boyd were separated by a significant distance, Lowe accepted Lewinski’s analysis that the emotional intensity of the event left him "shooting to save his life, rather than being focused to stop Mr. Boyd."

But after a CBC Vancouver investigation raised questions about Lewinski’s credentials and the objectivity of his expert testimony, the B.C. Police Complaints commission said it would never again use Lewinski as an expert.

The Alberta Serious Incident Response Team is now reviewing the case.

Lewinski’s use of the "inattentional blindness" theory has been rejected by U.S. judges in at least two cases. One judge threw out his testimony in the preliminary stage of the trial because he said it "lacked scientific foundation."

In an email, Lewinski defended his research.

"The science I share in the context of my work is held in the highest regard by top experts in the legal, academic, and criminal justice communities worldwide," he wrote, adding that his testimony is accepted by judges, juries, and large police  organizations in the majority of cases.

Research questioned

California civil rights lawyer John Burton scoffs at Lewinski’s claim that his research is held in high regard. Burton said there are experts who usually testify for one side or the other in civil and criminal cases, and he said most of these experts are credible, and "formidable."

But Burton said Lewinski "has the lowest reputation as just being somebody whose opinion is for sale, and it’s always to the police side."

Lewinski’s critics have publicly accused the police psychologist of providing research and testimony related to reaction times for police officers that they contend are either expanded or contracted to fit whichever scenario an officer needs to be exonerated.

"There are cases where I have noted that the explanation of the reaction time differs according to the case," said Roger Clark, a 27-year veteran of the Los Angeles County Sheriff’s Department. "That is troublesome."

Now retired in San Diego, Clark is an expert in police tactics and use of force who has sometimes been called to testify in the same cases as Lewinski. Clark’s expertise is based on his experience leading a specialized task force that arrested more than 2,500 people without firing a single shot.

"I have not seen any extensive, or any reasonable, replication of his work by independent sources," Clark said, adding that Lewinski has given testimony about reaction times that he does not believe are physically possible.

In perhaps his most controversial research article, "Why is the Suspect Shot in the Back?" Lewinski wrote that his test subjects, most of whom had never handled a firearm, could pull a gun from their waistbands, fully extend their arms, and fire in as little as .09 seconds — less than a tenth of a second.

By contrast, Lewinski has frequently testified that a police officer takes between 1½ to two seconds to respond to an attack, and draw and fire his gun.

Last week, Lewinski testified on behalf of a California police officer who shot and killed an 18-year-old man.

Lawyer John Burton said the officer’s defence hinges on his claim that he was physically able to react, and draw and fire his gun in less than a second. Lewinski testified research he had just conducted proved this was possible.

Burton said he obtained Lewinski’s own data, and none of the test subjects — all trained police officers — could draw and fire their weapons within that time.

"But he had no particular problem saying this superman officer, who he has never tested, would have no problem doing this in under a second," Burton said. "Even though his own data shows this couldn’t possibly be the case."

Credentials questioned

Burton and others have publicly questioned Lewinski’s credentials. Lewinski’s online biography states he has a doctorate in "police psychology" from Union University and Institute and that his work has been presented in both academic journals and at peer-reviewed conferences.

Union University is a distance-learning school. The university’s registrar, Lew Rita Moore, told CBC News that Lewinski actually earned a doctorate of philosophy, and chose police psychology as his concentration.

A review of the research articles cited by Lewinski on his website show about half were published in law-enforcement magazines, such as Police Marksman, as well as articles in academic journals.

"This is a man who has very thin credentials," Burton said. "He has carved out a niche as a professional witness on behalf of officers who are involved in shootings."

In his email to CBC News, Lewinski said he has been "consulted numerous times by investigators and prosecutors."

Lewinski however, did not respond to a request by CBC  News to provide an example of a case in which he had testified against an officer.

Clark says he is troubled that Lewinski also trains police officers, through seminars conducted by his Force Science Institute. The institute has run seminars for police officers across Canada, including Edmonton, Winnipeg, southern Ontario and, last month, Calgary.

The sessions teach officers about how stress and perception during a lethal encounter can affect an officer’s actions during, and memory after, the event.

The Institute also said it has determined how, after an officer uses lethal force, "investigators can best ‘mine’ officers’ memories and avoid interviewing mistakes that can put the officer, the investigator and the entire department in jeopardy."

In his email, Lewinski wrote: "Society and the police world deserve the best training we can provide and the best review of that action." He and his colleagues, he added, "do not advocate an, ‘act first and then ask questions later,’ approach."

But Clark said that if Lewinski’s seminars are reflective of his court testimony, he is training officers to use lethal force unnecessarily, and he is also training them how to justify it after the fact.

"This is about people’s lives," Clark said. "And I want to say it very bluntly: if people embrace this kind of mentality, people are going to die — unnecessarily. That is what needs to be said here."