Once the incriminating testimony of witnesses in a capital case is found by the beit din to be admissible and to prove the elements of the crime, the beit din asks the accused to bring on the defense.
The accused can attempt to undermine the incriminating testimony in three principal ways. He can attack the credibility of the testimony itself, he can attack the credibility of the witnesses themselves, or he can attack their eligibility to testify.
The way to attack the testimony itself is for the accused to bring eidei hachashah, which means a second set of witnesses who contradict the factual basis of the testimony offered by the first. For example, the second set may testify they saw the victim alive and well after the date of the alleged murder. Or they may testify the accused was not at the murder scene at the time of the murder but was with them.
If their testimony survives court examination, the result will be two conflicting yet admissible testimonies. Although each testimony is valid on its own, since each is contradicted by the other, the accused will be acquitted.
The way to attack the credibility of the witnesses themselves is for the accused to bring eidei hazamah, which means two witnesses who testify that the first set of witnesses could not possibly have witnessed the alleged crime. This is because at the time the crime is alleged to have occurred, the first witnesses were with the second set of witnesses in a different location – from which it would have been impossible to witness the crime.
In the case of eidei hazamah, the second testimony totally invalidates the incriminating testimony. The accused will not just be acquitted out of doubt, as he would be in the case of eidei hachashah; he will be acquitted because there is no credible evidence against him.
If both sets of witnesses have withstood the rigor of the court’s cross examination, why, one might ask, does the beit din believe the evidence of the second set of witnesses more than the first? There is no logical answer to this question. The law of eidei hazamah is a chiddush, a novel piece of legislation for which the Torah has given no explanation.
The way to attack the eligibility of the witnesses is for the accused to prove they belong to a category that is not eligible to testify. The Rambam lists ten such categories. Among them are witnesses who are either related to the accused, the judges, or each other. This disqualification applies to first-degree relatives such as brothers, second-degree relatives such as cousins, but not to third-degree relatives, such as great-grandchildren.
Also included in the list of ten ineligible witnesses are scofflaws. If witnesses for the accused can testify that the witnesses against the accused deliberately violated a Torah or rabbinic commandment in the past and for which the punishment is malkot, lashes, the witnesses against the accused will be disqualified.
Other persons included in the list of ineligible witnesses are professional gamblers whose roll-the-dice attitude to life may render their testimony less than reliable. Also ineligible are lenders who charge interest in contravention of Torah and rabbinic laws, and those who have received payment for their testimony.
After the court has given the accused ample opportunity to produce his witnesses and lay on his defense, the court adjourns to deliberate.
If the court decides to acquit the accused, it may do so on the same day the testimony was heard. Otherwise, the court must adjourn and deliberate through the night until it reaches a verdict. A guilty verdict cannot be rendered without a majority of at least two judges in favor of conviction and can only be rendered by day, not by night.
In the event of a guilty verdict, the execution would be carried out without delay so as not to prolong mental torture. During the interim period following the verdict and before the execution, the court would still entertain new evidence or arguments, if any, which might have a reasonable chance of reversing the guilty verdict.
Unlike modern executions, which are administered to the fully conscious, the Sanhedrin would administer a potion that effectively drugged the convicted prior to the execution.