The focus of each party in an action is to contest specific issues of fact and law offered by the opposing party. Joinder of issue, is a point in a lawsuit when the defendant has challenged some or all of the plaintiff's allegations of fact or when it is known which legal questions are in dispute--in other words, when both parties are accepting that the particular issue is in dispute the "issue is joined." Usually this point arrives when pretrial discovery is complete.
[Last updated in June of 2020 by the Wex Definitions Team]