Hankin (plaintiff) represented Spilker (defendant) in a prior action. In payment for his legal services, Hankin received seven notes from Spilker. The first was a demand note for $500, and the other six, each for $250, became due at three-month intervals. Spilker paid the $500 demand note, but failed to pay the second note when it became due. As a result, Hankin sued Spilker for the amount due on the note in the Municipal Court for the District of Columbia. Spilker filed a counterclaim seeking a determination that the $500 she had already paid on the demand note was full payment for Hankin’s services. Hankin prevailed against Spilker’s counterclaim and the court entered judgment in favor of Hankin. Subsequently, Hankin brought this action against Spilker in the Municipal Court for the District of Columbia on the five remaining notes after they became due. Spilker again argued that she had already paid Hankin the full value of his services. Hankin moved for summary judgment on the grounds that the prior judgment precluded Spilker’s defense in this subsequent action. The judge denied Hankin’s motion. After a jury trial, judgment was entered in Spilker’s favor. The Municipal Court of Appeals reversed and ordered judgment for Hankin. Spilker appealed.