Final answer:
The key concepts from Roman law used in the U.S. today are the presumption of innocence, 'innocent until proven guilty,' and the use of legal precedent, 'stare decisis,' which ensures consistent and stable judicial decisions.
Step-by-step explanation:
One staple of Roman law still used in the U.S. today is the concept of innocent until proven guilty. This revolutionary principle originated from Roman legal traditions, indicating that an accused person should be presumed innocent until evidence sufficiently demonstrates their guilt. This contrasts with many ancient justice systems that presumed the accused guilty until proven innocent. Additionally, the Roman practice of using precedents in legal decisions, known as stare decisis, is a cornerstone of the American legal system. This reliance on past rulings provides consistency and stability in legal interpretations, enhancing the legitimacy of the judicial process.