That sounds like a very wild situation, and I hope that the 4-year old son will be okay. However, despite all that you have stated, I cannot determine if the police were even responding to the medical marijuana. They could have been acting based on some other crime. I would advise against posting more information about the situation on this forum. Talk to a local attorney immediately so that they can get all of the details in a protected attorney-client conversation.
The police may have violated the law, but it would take a thorough examination of all of the facts, including statements from the police, before your situation can be evaluated. You and your friend both need a civil rights attorney AND a criminal defense attorney who specialize in medical marijuana situations.
You should contact a civil rights attorney. If you need me to refer you to one, you can call my office and will try to give you a few numbers to try.
The answer above is only based upon the limited information provided. The answer is limited and my review is likewise limited, and thus the response is not intended to be acted upon as legal advice. Although licensed in numerous states, I am currently only licensed to practice law in the state of Nevada. No attorney-client relationship is formed until you sign an attorney-client agreement with my office. Any information provided is for discussion purposes only and there is no attorney-client relationship formed. Only general legal information is provided. Each case is unique and accurate legal advise would require review of all details and documents for each specific case. It is possible that the comments here, while meant to be helpful, may in some cases not be complete or accurate.