What is No Case To Answer?

Legal Definition
No case for the defendant to answer (sometimes shortened to no case to answer) is a term in British criminal law, whereby a defendant seeks acquittal without having to present a defence. The plea is also occasionally, although rarely, used in civil cases where it is alleged that the pleaded case and/or evidence do not meet the minimum threshold to establish liability.

At the close of the prosecution's case during a criminal trial, the defendant may submit to the judge or magistrate that there is no case for the defendant to answer (similar to a motion for a directed verdict in a United States court). If the judge agrees, then the matter is dismissed and the defendant is acquitted without having to present any evidence in their defence. If the judge does not accept the submission, the case continues and the defence must present their case.

Because a judge's refusal to uphold such a submission may potentially bias a jury's decision, a submission of no case to answer is usually heard in the absence of the jury.
-- Wikipedia
Legal Definition
Defendant’s submission that the opposing party has no case to rebut, with no evidence, and no legal grounds. End of the trial and release of the defendant comes from a successful no-case submission. Also known as no-case submission.