Students break the law all the time - not paying for a TV licence, drug taking etc but they turn a blind eye then, don't they?
They certainly don't turn a blind eye at all. All was in the handbook and rules when my DD1 started uni back in 2013. Since then she has also had part time jobs working on the security team around the Union at her uni and saw all sides to it. They are super strict, decline entry to people who are already far to drunk and abusive, or suspected of drug taking. They have to close up the night clubs there if there is any health and safety issue, and on top of that they have to deal with drunken twattery, take loads of abuse and call ambulances and police as and when necessary.
OP, it must be very worrying to you, and quite a shock. However, I also think that there could well be more to it than you have been told. You need to get to the bottom of it somehow, though I guess that your DD will either clam up or for now keep repeating the same story.
If your DD wants you to be there in support at her disciplinary hearing then that might be your tool to ensure that you have everything there is to hand. I would say that I would be willing to be there for her, but would point out that EVERYTHING will be discussed there and will come out, so she should be under no illusions that only her story will be told. I would say that I can only offer meaningful support if I am fully in the picture, I would need to see all emails and paperwork so that I could understand everything, better support her and not be in line for any more unpleasant surprises.
I think that her personal tutor will want her permission to speak to you even though your DD is still technically a minor at 17. The great majority of uni students are over 18 and unis have to abide by confidentiality and Data Protection rules.
Good luck, and stay strong.