If a president attempted to influence a Supreme Court decision by directly contacting a judge, it would violate the idea of separation of powers because the judiciary branch is meant to be independent from the executive branch. The president's actions would be seen as an attempt to unduly influence the judicial branch, undermining the system of checks and balances that are meant to keep each branch of government in check. This could lead to a violation of the principle that each branch of government should operate independently and free from interference from the other branches.
