Police officers are public employees, so why is it so hard to find out basic information about their past misdeeds, even after they, for example, kill someone on camera? Section 50-a of New York's Civil Rights Law shields cops' personnel records from public scrutiny, and as a WNYC report lays out, does so more stringently than laws in most other states in the country.

Only 23 states have some level of confidentiality for police disciplinary records, and New York is just one of three with rules specifically protecting law enforcement officers, according to the radio station's sweeping review. It is also one of the few states with no safeguards in place to disclose internal police records when it may be in the public interest.

A Washington, DC police union head told WNYC such restrictions prevent "witch hunts of police officers," and indeed, New York's protection became law in 1976 because of fears about possible distortion of petty issues in court.

"That could possibly sway a jury to allow a criminal to be set free when they really shouldn't be set free," Detective's Endowment Association president Michael Palladino told the station.

Conversely, the state-imposed secrecy can keep judges, jurors, and defense attorneys unaware that they're dealing with a cop who has documented credibility issues. For instance, Bronx cop Luis Rios reportedly pleaded guilty in 2012 to internal NYPD charges that he falsely smeared colleagues, lied to Internal Affairs, and lied about an on-the-job-injury, a history that could have had big implications for people he arrested in the following years. Yes, Rios stayed on the job, as did 41 of 59 officers with documented false statements identified in the Commission to Combat Police Corruption's annual report published last year.

Prosecutors are supposed to turn over information about cops' disciplinary histories, but they're not required to research them in the first place, and often don't.

The state's Committee on Open Government recommended last winter that the legislature repeal the blanket secrecy provision, but committee director Bob Freeman said he isn't optimistic.

"It seems to be an issue that many are not willing to touch and my belief is, and maybe I shouldn't say this but I will—I believe that the unions are exceedingly powerful and members of the legislature don't really want to upset them," Freeman said.