§ 136.010 When issue of fact arises

When a defendant pleads not guilty, that plea creates what's called an "issue of fact." This means there's now something for the court to actually decide: whether the person did what they're accused of doing.

Before this plea, the case is mostly about paperwork and charges. Once someone says "not guilty," the case shifts into a new phase. Now the state has to prove its case, and a judge or jury will need to look at evidence and testimony to figure out what really happened.

This is basically the starting point for a trial. Without a not guilty plea, there's nothing to argue about in court. The plea is what sets up the need for a trial in the first place.