People v. Nicholson

A defendant who has knowingly and voluntarily pleaded guilty may not thereafter attack the judgment of conviction entered thereon by coram nobis or other post-conviction remedy on the ground that he had been coerced into making a confession and that the existence of such coerced confession induced him to enter the plea of guilty. If a defendant desires to contest the voluntariness of his confession, he must do so by pleading not guilty and then raising the point upon the trial; he may not plead guilty and then, years later, at a time when the prosecution is perhaps unable to prove its case,…