The phrase "inadmissible evidence" refers to evidence that cannot be used in a court of law because it is not allowed or accepted under the rules of evidence. Full definition
Impeaching Your Own Witness: Even though Evidence Rule 607 authorizes a party to impeach the credibility of his own witness, a party is forbidden from placing a witness on the stand if his sole purpose in doing so is to present otherwise inadmissible evidence cloaked as impeachment. (the-barristers-toolbox.com)
On television, we often see attorneys make long - winded objections and in doing so, present inadmissible evidence to the jury. (lawyerist.com)
The Crown's reliance on inadmissible evidence would subvert this process (Barr at paras 9, 13). (ablawg.ca)