To obtain a conviction against a person facing assault charges. Midland prosecution has to meet all the elements of whatever offense they are saying the individual has committed. For example, if they accuse someone of intentionally making unwanted contact. They must prove that contact occurred and that the contact was intentional.
Suppose an individual was on a bus which made a sudden stop. And they fell into another person who then claims the individual made unwanted contact. In that case, the prosecution must prove that the individual intentionally or knowingly caused the contact. The bus stopping scenario would be difficult to prove because the accused individual has a reasonable defense.