At all types of court, the issue of "hearsay evidence" can be important.
A definition: I can testify to what I saw. I can testify to what I smelled. But if I testify to words I heard, and the speaker of those words is absent or denies my testimony, then I have given hearsay evidence, and the court properly ignores it (and asks jurors to ignore it too).
How can this matter? Here is how it mattered to me. I got a ticket for parking in a "Snow Emergency" zone during a "Snow Emergency". It was a costly ticket then (about 1980) and it would probably be much more costly nowadays.
Maybe the cop won't show up. He did.
Maybe the cop will leave out the date or time or place or something else vital to the crown's case. Nope, he gave good testimony.
I said, "How did you know that a Snow Emergency was in effect?"
He replied, "My Sergeant told me."
The magistrate took over for me, to my astonishment. He asked, "Is your Sergeant in this courtroom?" The answer was negative.
The magistrate told the cop he could go and sit down. This action was my clue to stay silent, and I did!
The magistrate explained that the cop had given hearsay evidence, an account of what an absent person said. He said that the information given was vital to the crown's case, but could not be relied upon because it was hearsay, so he was dismissing the case against me. He went on to tear a strip off me for parking on Richmond Street during the winter's worst snowstorm, but that rolled off my back.
That is really the end of the story, and you may say the cop was stupid not to bring his sergeant along, but what if he had? The sergeant would corroborate the cop's words, then I would ask him, "How did you know there was a snow emergency at the time?"
Unless the whole chain of command had tagged along to the courtroom, I would eventually get the hearsay evidence dismissed. Of course, if the top banana had showed up and said, "Begorrah, I am the Lord High Pooh-Bah in charge of declaring Snow Emergencies, and I so declared!" then I would be found guilty.
If you treat these things as a game, sometimes a costly game, you can enjoy some of the process. I think my record is 11 trials, 8 dismissals.
I wish you better luck!