Historically, the most significant type of penal bond was the penal bond with conditional defeasance. A penal bond with conditional defeasance combined in one document the bond (the promise to pay a specified amount of money) with the contractual obligation. It did this in what the historian Brian Simpson called a ‘topsy-turvy’ fashion by printing the bond on the front of the document and the condition, whose performance by the obligor would render the bond void (referred to as the indenture of defeasance), on the back.
