How did oaths function in traditional sharia court procedures?

In traditional sharia court procedures, the oath served as a critical mechanism for resolving cases where evidence was insufficient to meet the strict requirements of shahādah (oral testimony).1

The function of the oath was as follows:

• Property Claims: In most property-related claims, a plaintiff could satisfy the burden of proof by providing one witness combined with their own solemn oath regarding the truth of their claim.1
• The Oath of Denial: If a plaintiff or prosecutor produced evidence that failed to meet the rigid standards of shahādah, the qadi would offer the defendant the "oath of denial." If the defendant properly swore this oath, judgment was secured in their favor.1
• Refusal: If a defendant refused to take the oath of denial, judgment was typically granted to the plaintiff, provided that the plaintiff, in some instances, was willing to swear an oath themselves.1

Because the qasam (oath) is a pledge made to God, it carried significant moral weight, as a false oath was considered a grave danger to one's soul. This formalistic system ensured that the verdict followed automatically once the oath was either administered or refused.21