In civil cases infants appear by their guardians ad litem; lunatics by their committee; companies by a solicitor; friendly societies by the trustee or other officer appointed to sue or be sued on behalf thereof.
The effect is to acknowledge the court's jurisdiction over the party who has made the appearance, and to waive any irregularity in service or commencement of proceedings.
Before the advent of this procedural device, a defendant faced the dilemma of either allowing his property to be seized with no defense and sold at sheriff's sale to partially satisfy the claim against him or, on the other hand, to appear in court to dispute the claim but in the process expose himself to the full in personam jurisdiction of the court and therefore the entire amount in controversy.
The equivalent of such an appearance is possible in U.S. federal courts, for the defendant may make a motion to dismiss for lack of personal jurisdiction.
Beginning in the late 1990s, adherents of the sovereign citizen's movement have attempted to use the special appearance to question the jurisdiction and competence of courts where the point is moot.