u/FalcosLiteralyHitler

I know nothing about law. I am watching law and order with my wife. The defendants "just discovered" evidence pertinent to the case and tries to present it during trial (handing the prosecution the evidence mid trial). The judge in the show calls them to his quarters before going further.

In my head this isn't presented during discovery they can't just surprise them in court. My wife says since it was discovered mid trial it can be presented per the discretion of the judge. Who is right?