When can a defendant in a criminal trial introduce evidence?

Question

I was watching a criminal speeding trial in Texas a few weeks ago. The defendant was acting pro se. A police dash-cam video apparently existed of the incident and the defendant was in possession of it.

The prosecution did not want the police video introduced as evidence. The defendant attempted to introduce it after the prosecution rested and the officer was on the stand. He was asking that the video be played so that the officer could testify as to whether it was his video or not.

But the judge ruled it could not be admitted even before showing it. I remember the prosecutor argued it wasn't relevant. But the video was not shown either in front of the jury nor did the judge even ask the jury to leave in order to show it.

Is that really common? I find it incredible that this video wouldn't be relevant. I also find it weird that the prosecution wouldn't want it admitted being that the defendant must have thought it to be exculpatory. The defendant seemed to be trying to lay foundation and the prosecutors objections did not include failure to lay foundation.

Answer 1

There are all manner of reasons that evidence can be excluded at a trial, most of which are set forth in rules of evidence.

If the evidence was not admitted on the grounds of relevance and the charge was speeding, I presume that the reason that it was found not be to relevant was that it was not possible from a video to determine how fast someone was driving and there was no dispute in the case over who was driving. If the defendant could have articulated some reason that the video was relevant to those points, perhaps it could have been admitted. But, as if often the case, pro se defendants are usually not articulate enough to set forth a legally relevant reason that evidence should be admitted.

Unless the defendant could show that the video showed something allowing a jury to determine whether or not the law was violated, it probably wouldn't be relevant and I can't easily imagine how it would be relevant, but perhaps there was some special facts or circumstances that might show, for example, that the speed gun was actually picking up another vehicle.