Both the demurrer and plea must be put in, in open court, either at the time of the arraignment or at such other time as may be allowed to the defendant for that purpose.
Idaho Code § 19-1702
Demurrer or plea — When interposed
Current official text: Idaho Statutes (Idaho Legislature). Digitized from the UniCourt Code Improvement Commission public-domain capture. Reproduced from public-domain Idaho statutes; confirm against the official source for the current text. Not legal advice.