My boss left early today, my project wrapped up early, so I have a little more time to read today than normal. First off, since I know someone is going to say “there goes the damn conservatives shreading the Constitution again”, here is the actual text of the 4th Amendment:
The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.
There is nothing there about knock vs no knock, so any laws up to this point were simple interpretation.
And yes, several states passed laws allowing no-knock warrants, but most were repealed because of court challenges. There are exclusions to the existing knock requirement.