The Day of Reckoning

Literally, the Day of Reckoning (capitalized) is, in Christian religion, the day of God's final judgment upon all nations. Figuratively speaking, the day of reckoning (not capitalized) for a person accused of a crime is the day upon which a verdict is rendered, finding the accused guilty or innocent.

Example: In medieval English law (let's say, 1066 to 1350 A.D.), an "appeal of felony" was a private prosecution against a person for some kind of crime. With rare exception, the appeal had to be made by the person harmed by the action. In the case of a murder, the wife of a murdered man could make the "appeal of felony." 

In these times, such lawsuits were usually for some kind of financial compensation. These lawsuits were usually settled before the day of reckoning. If both sides came to terms, money or some other form of compensation was paid to the spouse of the victim.

That is to say, usually, a settlement would be reached before a judge decides whether the defendant is guilty or innocent. If found guilty of murder, the defendant would be executed through hanging! Clearly, there would be little point in settling the case after the day of reckoning, with the defendant either found innocent (and owing nothing) or guilty (and paying with his life!).