"Heat of passion" is a legal defense argument usually raised in murder, attempted murder or manslaughter cases, and is intended to eliminate the element of premeditation. A defendant may use it when they want to argue that their actions were provoked by intense and immediate emotions such as fear, rage, anger or terror. A key issue in the defense is adequate provocation, a situation that might naturally cause a reasonable person, in the passion of the moment, to lose self-control and act on impulse without taking an opportunity to reflect on the outcome.
An example of this defense could be illustrated by a case in which a spouse or lover finds their partner sexually involved with another person, goes into a rage and kills one or both of them. If the defendant acted immediately after or during the provocation, without taking the time to rationalize their actions, it may eliminate the element of premeditation and may help reduce a person’s criminal charges or sentence. It is sometimes called the "Law of Texas" since juries in that state are supposedly lenient to lovers who wreak their own vengeance. Heat of passion is not used to dispute whether a person is responsible for their actions, but to defend the particular state of mind that a person was in when those actions were committed.
When the law defines an action as a criminal offense, that definition is usually very specific. Legal definitions of a crime commonly contain a number of circumstances, or elements, that must exist. Premeditation is one element clearly stated in the definition of many crimes, referring to the thoughts, plans or ideas that a person has relative to the crime before it is actually committed. The heat of passion defense disputes any intentions to commit the crime before the defendant was placed in the situation where the crime was committed, and is used to argue that a person’s actions were impulsive.
But premeditation is not the only issue to consider when arguing heat of passion: in order to effectively apply this argument the circumstances must generally be such that another reasonable person, in a similar situation, would have reacted in a similar fashion. This means that the defendant's mental state at the time of the offense has to be taken into account, and it must be determined that their mental state is "reasonable" even though they were in an obvious state of extreme emotional duress. In an example such as the one above a judge or jury would need to consider whether adultery or infidelity could cause another person of sound mind to lose control and commit the same crime under the same circumstances.
Because the heat of passion argument in a legal defense depends on a person’s mental state, there is generally no question about whether the accused actually committed a physical act. Instead, the defense is generally used for two purposes; in some cases it may determine the actual charges as applied to a person’s actions, for example in reducing a charge of murder to manslaughter. In other cases where the charges are appropriate to the case, the heat of passion defense may convince a judge or jury to lessen the sentence.
The state of Texas recognizes four different categories of homicide that can result in criminal charges: Capital Murder, Murder, Manslaughter, and Criminally Negligent Homicide. These charges depend on a number of elements, including the circumstances surrounding the homicide and whether criminal intent was involved. Although many states make a legal distinction between voluntary and involuntary manslaughter, Texas State Law combines both concepts into a single definition but still allows for differing circumstances: i.e. intoxication manslaughter (recklessly causing the death of another while intoxicated ) and vehicular manslaughter (recklessly causing the death of another while driving a vehicle or vessel).
Murder cases in Texas are generally prosecuted as a first degree felony, which carries a sentence of up to 99 years in state prison and/or a fine of no more than $10,000.
In the Texas State Penal Code (Sec. 19.02.) "Sudden passion" is defined as "...passion directly caused by and arising out of provocation by the individual killed or another acting with the person killed which passion arises at the time of the offense and is not solely the result of former provocation."
The law further states in paragraph (d) that "At the punishment stage of a trial, the defendant may raise the issue as to whether he caused the death under the immediate influence of sudden passion arising from an adequate cause. If the defendant proves the issue in the affirmative by a preponderance of the evidence, the offense is a felony of the second degree." In this situation the heat of passion argument is central to discriminating between first and second degree charges.
RETHINKING HEAT OF PASSION: A DEFENSE IN SEARCH OF A RATIONALE Dressler, Joshua Journal of Criminal Law & Criminology; Summer 1982, Vol. 73 Issue 2, p421
Texas State Penal Code, Title 5. Chapter 19: Criminal Homicide
Texas Manslaughter Laws