Arrogance is the greatest threat to the criminal justice system, particularly when it comes in the form of a scientist whose work is vital in so many cases.

Last week, our investigative reporter David Wren detailed the major problems with an 18-year-old rape case during which a man was sent to prison despite enough questions that an independent forensic expert who examined it said there’s reason to believe there was a tampering with evidence designed to “make a case” instead of assure justice.

There’s reason to be disturbed by an appeals process that is designed to protect the system more than fully examine legitimate questions that are raised after a conviction.

There’s reason to be disturbed by the thin threads upon which that conviction rested.

But most disturbing is the claim made by Emily Reinhart, a serologist who still works for SLED’s forensics laboratory.

When asked during trial if she could have made a mistake or if anyone else checks her work, this is what she said:

“I do my own analysis. … I have never made a mistake in case work.”

There is talk of conspiracy, which always sounds far-fetched, given that no one wants to believe that a professional paid by taxpayers would ever do such a thing.

Believing in a conspiracy is not even necessary when a scientist so clearly flaunts basic scientific understanding, that the work they do and the conclusions they reach are about probability, not prophecy.

Reinhart has never made a mistake? She’s perfect?

Her thinking is flawless?

It is a preposterous claim, the kind that could easily lead a proud person to, instead of owning up to a mistake, find a way to hide it for fear of being found out for what she really is, an intelligent human being who happens to be as imperfect as the rest of us.

Another basic tenet of science is that a finding becomes more credible when another scientist can conduct independent tests on the same evidence and reach a similar conclusion.

In this case, other scientists and investigators could not duplicate what Reinhart found.

And she contradicted her own testimony after an important piece of evidence went missing.

I do not know if the right man is behind bars for that 1994 rape.

I do not know if the serious mistakes raised in this case were happenstance or purposeful.

I do not know how I’d feel if I was the victim who had to hear so many questions raised about a man she believes raped her.

But I know that a criminal justice system that pretends to be perfect is the kind prone to the most egregious mistakes.

We often brag about our system, as we do for just about everything that is American, that it must be the best, because early in life, we are told to trust authorities, not question them.

We don’t much like considering the possibility that the view of the criminal justice system we’ve long been taught could be wrong, that it sometimes leads to awful things, including wrongful convictions and a process that makes it harder for certain groups to receive justice than others.

Reinhart’s mistake is that she can’t acknowledge any; ours is that we force people like her to grab tightly to that type of illogic and not let go.

A few years ago, I was covering a case in Horry County.

The prosecutor asked the judge to have me removed from the courtroom – because I had dared to write about flaws in the system and the need for reform.

He was offended that such questions would even be raised.

But they must.

Contact ISSAC J. BAILEY at 626-0357, ibailey@thesunnews.com or via Twitter.com at @TSN_IssacBailey.