The phrase "sacred principle" refers to a fundamental belief or value that is highly respected and regarded as holy or deeply significant. Full definition
They treat all offenders the same, when the most sacred principle of American sentencing law is that punishment should fit the individual and the crime. (news.lawreader.com)
Many students and teachers describe the school's generosity as an almost sacred principle. (nytimes.com)
Then there's that most sacred principle in the American criminal justice system that says «innocent until proven guilty.» (hudsonvalleyone.com)