A more thorough explanation:

Appellum de felonia is a historical legal term that refers to the appeal of felony. It was a legal procedure used in medieval times where a person accused another of a crime, demanded proof of innocence by wager of battle, or informed against an accomplice.

For example, if someone was accused of stealing, the victim could make an appeal of felony and demand that the accused prove their innocence by fighting a duel. Alternatively, the victim could inform against an accomplice and accuse them of being involved in the crime.

Another example would be if someone was accused of murder, the victim's family could make an appeal of felony and demand that the accused prove their innocence by fighting a duel.

The examples illustrate how appellum de felonia was used in medieval times as a way to determine guilt or innocence. It was a primitive form of justice that relied on physical strength and combat to prove one's innocence. The procedure was often used in cases where there was little or no evidence to prove guilt or innocence, and it was believed that God would intervene and ensure that the innocent party emerged victorious.