When the defendant does not show up in court to contest the validity of the claim, a judgment will be rendered in favor of the non-defaulting party automatically, which is called a "default judgment".
Example of a state statute on judgment by default.
Texas Civil Procedure Rules speaks about Judgment by default. The relevant sections read as follows:
Tex. R. Civ. P. 239: Judgment by Default
Upon such call of the docket, or at any time after a defendant is required to answer, the plaintiff may in term time take judgment by default against such defendant if he has not previously filed an answer, and provided that the citation with the officer's return thereon shall have been on file with the clerk for the length of time required by Rule 107.
Tex. R. Civ. P. 239a Notice of Default Judgment
At or immediately prior to the time an interlocutory or final default judgment is rendered, the party taking the same or his attorney shall certify to the clerk in writing the last known mailing address of the party against whom the judgment is taken, which certificate shall be filed among the papers in the cause. Immediately upon the signing of the judgment, the clerk shall mail written notice thereof to the party against whom the judgment was rendered at the address shown in the certificate, and note the fact of such mailing on the docket. The notice shall state the number and style of the case, the court in which the case is pending, the names of the parties in whose favor and against whom the judgment was rendered, and the date of the signing of the judgment. Failure to comply with the provisions of this rule shall not affect the finality of the judgment.
Tex. R. Civ. P. 240: Where Only Some Answer
Where there are several defendants, some of whom have answered or have not been duly served and some of whom have been duly served and have made default, an interlocutory judgment by default may be entered against those who have made default, and the cause may proceed or be postponed as to the others.
Tex. R. Civ. P. 241: Assessing Damages on Liquidated Demands
When a judgment by default is rendered against the defendant, or all of several defendants, if the claim is liquidated and proved by an instrument in writing, the damages shall be assessed by the court, or under its direction, and final judgment shall be rendered therefore, unless the defendant shall demand and be entitled to a trial by jury.
Tex. R. Civ. P. 243: Unliquidated Demands
If the cause of action is unliquidated or be not proved by an instrument in writing, the court shall hear evidence as to damages and shall render judgment therefor, unless the defendant shall demand and be entitled to a trial by jury in which case the judgment by default shall be noted, a writ of inquiry awarded, and the cause entered on the jury docket.
Tex. R. Civ. P. 244: On Service by Publication
Where service has been made by publication, and no answer has been filed nor appearance entered within the prescribed time, the court shall appoint an attorney to defend the suit in behalf of the defendant, and judgment shall be rendered as in other cases; but, in every such case a statement of the evidence, approved and signed by the judge, shall be filed with the papers of the cause as a part of the record thereof. The court shall allow such attorney a reasonable fee for his services, to be taxed as part of the costs.