noun
mistrial
MIS-try-uhl/ˈmɪstraɪəl/
A trial that ends without a valid verdict.
The judge declares a mistrial after a juror contacts a witness.

Etymology
The prefix marks a trial as having gone wrong: serious errors invalidate its outcome. It describes a defective legal proceeding, rather than simply an unfavorable verdict.
In context
if the threat is to declare it a mistrial as opposed to a hung jury, that's because of some form of impropriy that was carried out in the process.
More examples
- A deadlocked jury can lead to a mistrial.
- After the mistrial, prosecutors prepare to try the case again.
- Serious procedural errors sometimes result in mistrials.
Forms
mistrial · mistrials