This is a complex question that will be inevitably be determined on the basis of the totality of factual circumstances. Schools in California are increasingly taking the position that they have a right to remove persons from their student population whom they have reason to believe are dangerous or potential risks for other students, even if the factual bases for that belief are incidents that occurred away from school. Obviously, this can be a very dangerous position with enormous consequences for students. But the school's position is probably supported by standards for potential civil liability, so we cannot expect that a bright line will be created that limits school discipline to response to misconduct occurring at the school premises. The school's position is even stronger if it can show -- as it usually can -- that the risk factors are based on personal relationships and connections that would not exist but for the fact of the common school.
The bottom line is that, depending on the factual circumstances of this matter, you may be at risk for expulsion or other serious discipline, and you need to challenge any such disciplinary action by utilizing the school's administrative appeal process. It would be wise to retain legal counsel as the consequences of expulsion to your subsequent educational opportunities and future employment can be very severe and long-lasting.
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