A motion in limine is a pre-trial motion, but what distinguishes it from other motions, like a motion to suppress statements or quash arrest, is that it can usually be ruled upon with only brief legal argument. Indeed, many motions in limine are agreed to.
For example, just before I go to trial, I have a standard list of motions that I file with the court. These include requests that witnesses be excluded from the courtroom when others are testifying, that my client be allowed to appear in regular clothing (if he is in custody), and that the prosecution refrain from mentioning that I’m a public defender. The prosecution typically agrees to these.
My list also includes that the prosecution not be allowed to reference my client’s prior criminal history, should he choose to testify. The prosecution always objects to this, and we then ask the court to engage in the prejudicial/probative value balancing test with which I suspect you are already familiar.
These issues are best brought in a motion in limine rather than during trial because, if you ask for a ruling after the trial has already happened, it’s probably too late. For example, you can’t make a motion to exclude witnesses after the witnesses have already heard some of the testimony.
Aside from these types of motions in limine, you should also litigate any significant evidentiary issues that you think might arise before the case starts.
For example, if your case hinges on the admission of a statement that is arguably hearsay, get a ruling on that before trial. Don’t go to trial, have the judge rule against you, and then be left speechless. Instead, if you bring it in a motion in limine, you can use that statement with confidence – assuming that you win the pre-trial ruling. If you lose it, at least you have enough time to look for another way to attack the charges.
Of course, you can’t anticipate all of the surprises (which is part of the fun), but motions in limine are a good way to lessen some of the stress of a trial by taking away some of the uncertainty.