After shooting an unarmed black man to death last week, San Antonio Police Officer John Lee now faces a lengthy process to determine whether he should remain on the force.

It’s a disciplinary process skewed in his favor — an excessively legal one that U.S. Rep. Joaquin Castro suggested is “broken,” and one that Police Chief William McManus on Wednesday acknowledged he would “like to see a deep discussion into.”

That’s an evolution from last week, when McManus, a day after the shooting, told me, “I don’t think there needs to be a shift toward more punitive (discipline). … There needs to be, in many cases, a change in the way we do things, a change in tactics.”

Lee, though, apparently disregarded well-established tactics in the killing of Antronie Scott.

Wanted on two felony warrants, including felon in possession of a firearm, Scott, 36, was parking a Mercedes at a North Side apartment complex when Lee pulled his patrol car behind the sedan, got out and “approached the driver side of the (suspect’s vehicle),” according to a police report.

Lee “drew his service weapon and ordered (Scott) to ‘show me your hands’ at approximately the same time (Scott) swung the drivers door open and spun to his left,” the report stated.

Believing a cell phone in Scott’s hand was a weapon, Lee shot him once in the chest.

“It seems as though the officer made a couple of mistakes in his approach and didn’t allow for enough space to make the proper decisions,” Councilman Alan Warrick, who is black, told me on Wednesday. “It was just too close, and it wasn’t that urgent a situation.”

Whether those “mistakes” end up costing Lee his job as a police officer might not even be up to McManus. That’s because any punitive ruling by the police chief is subject to an appeal process.

A 2011 paper, “Police Discipline: A Case for Change,” described the problems with such arbitration.

“The disciplinary appeal processes often weaken the purpose of discipline,” stated the paper, published by the Harvard Kennedy School of Government. “Police executives’ disciplinary decisions are frequently overturned or reduced by review boards and arbitrators, undermining the impact of the discipline.”

The paper cited a study in Cincinnati that found “when fired officers appeal to an outside arbitrator, they get their jobs back every time.”

In the past seven years in San Antonio, five of 13 rulings were overturned or reduced by arbitrators on appeal — and all five were initially terminations, according to Deputy City Manager Erik Walsh.

“I think to a certain degree, (arbitration) can hamstring a police chief from making good decisions,” Walsh told me. “I think, inherently, arbitration usually lands on the side of the employee.”

Taj Matthews, executive director of the Claude and ZerNona Black Developmental Leadership Foundation, pointed to arbitration — and the police union’s abuse of it — as an obstacle to weeding out bad officers.

“What we have out-of-control is the police union with (union president) Mike Helle because you have a structure where it is very hard to terminate a police officers’ employment,” Matthews said.

Castro, D-San Antonio, also flagged the union.

“To achieve the reforms that Chief McManus wants, we need to review the disciplinary process,” the congressman said. “The troubling thing is, it looks like that disciplinary process may be broken. Because the union and the city have not agreed to a new contract, now is the time to undertake that review.”

Helle on Wednesday defended the appeal process.

“The congressman, I don’t know if he’s using this as a platform that he wants (to use) to run for re-election,” he said. “What do you have against police officers having the same process that everybody else does? I don’t know if it’s ignorance or his failure to understand the process.”

McManus, at least, knows the process.

“I’d like to see a deep discussion into the disciplinary process,” McManus told me. “I think each aspect of the disciplinary process should be examined.”