Motions In Limine are related to whether or not a specific evidentiary item should be admissible or excluded during trial, or if it is too prejudicial to the defendant. Under Evidence Code 402, this concerns issues such as prior convictions and prior bad acts, voluntariness of statements made by a defendant, Miranda, hearsay, and privilege objections that must be litigated in a suppression hearing pursuant to Evidence Code 1538. Objections to the introduction of evidence under Evidence Code 402 may be followed by voir dire examination of a witness.  Any pre-trial ruling by the court on an in limine motion is not binding on the trial court and the prosecution may attempt to offer the same evidence during trial. During trial, the court has discretion to accept the prior ruling or allow for relitigation of the issues.

Commonly, in limine and foundational objections are made at trial outside the jury's presence to avoid prejudicial publicity. However, to avoid delays at trial, a party may file a motion at the earliest possible time before the jury is even selected.  When seeking exclusion or evidence, the moving party must specifically identify why the evidence is inadmissible. To say generally, for example, that jailhouse informants are not reliable, would not be specific enough to meet the burden of proof for exclusion of proffered evidence.
 
A hearing is typically required only regarding whether or not the defendant waived his rights voluntarily, and that too is typically conducted outside the presence of the jury.  At a preliminary fact hearing only admissible evidence may be considered.  Further, all rulings as to the admissibility of evidence must be made on the record or they are waived for appeal.
 
If the court grants a motion in limine, it excludes a specific item of evidence and instructs counsel to not refer to that evidence during proceedings.  Admissibility of a preliminary fact, as first determined by the judge, may be based on forensic tests, character evidence offered for some other purpose, reputation of victim for dangerousness in a self-defense case, hearsay statements, authenticity of evidence and identification.  Either party seeking to offer the evidence at trial must show that a jury could find this fact is true by a preponderance of the evidence. Once this showing has been made, the court submits the issue to the jury for consideration. If the jury finds that this fact was established by a preponderance of the evidence, it will be considered as evidence.