Why was placing the burden of proof for land ownership on Mexican Americans contrary to US Legal practice?

Placing the burden of proof for land ownership on Mexican Americans was contrary to U.S. legal practice because it reversed the foundational principle that the claimant must prove their case rather than the accused. Traditionally, in U.S. law, property rights are presumed to be valid until proven otherwise, meaning that established ownership should not require individuals to prove their rights continuously. This practice unfairly disadvantaged Mexican Americans, undermining their legal rights and reinforcing systemic inequalities following the U.S.-Mexican War and subsequent land dispossessions.