In most legal proceedings, one party has a burden of proof, which requires it to present "prima facie" evidence for all of the essential facts in its case. If it cannot, its claim may be dismissed without any need for a response by other parties. A "prima facie" case might not stand or fall on its own; if an opposing party introduces other evidence or asserts an affirmative defense, it can only be reconciled with a full trial. Sometimes the introduction of "prima facie" evidence is informally called "making a case" or "building a case".