text: There are really only formal amendments, as defined in Article V.\n\nI guess you can consider US Supreme Court holdings, which interpret provisions of the Constitution, to be informal where they are not reflected in the actual text. But that's not really an amendment.\n\nExample. The Constitution by its text does not require Miranda warnings, nor does it require exclusion of evidence that is illegally obtained. Both of those are the result of Supreme Court holdings,  based on the intent of the requirements and the means by which the explicity provisions of the text can be enforced in real life.\n\nDo you consider those interpretations or informal amendments?