The article describes how about half of the district attorneys and detectives that are presented with incontrovertible evidence of the innocence of someone they have convicted will stoutly defend the verdict. There are many possible reasons why government officials react to evidence with denials. However, positions of authority attract authoritarian personalities. Nobody likes to have their mistakes pointed out, but authoritarians really don’t like to have their mistakes pointed out.
Another interesting question is why do those responsible for prosecutions make so many mistakes in the first place? One factor is that government officials do not generally pay for their mistakes even when those mistakes are uncovered. When someone wins a suit for wrongful conviction, the taxpayer ends up paying. The officials involved may be embarrassed, but they suffer no real penalty. Such a system constitutes a license for abuse.