In law, bifurcation is a judge's ability to divide a trial into two parts so as to render a judgment on a set of legal issues without looking at all aspects. Frequently, civil cases are bifurcated into separate liability and damages proceedings. Criminal trials are also often bifurcated into guilt and sentencing phases, especially in capital cases.
In Federal Court judges have wide discretion to structure trials. Factors evaluated will include congruence of issues, complexity for the jury, and possible prejudice to any of the parties. American Federal Rules of Civil Procedure, Rule 42(b) allows the court to decide issues contained in separate trials.
State procedures differ widely.
In some states, a defendant who has raised the defense of mental disease or defect will automatically create a bifurcated trial. In the first stage of the trial, both sides present evidence and testimony designed to establish that the defendant is either guilty or not guilty. If the defendant is guilty, the issue of mental disease is presented.