My name is ***** ***** I am a NSW Solicitor. Thank you for your question, and will do my best to assist you with your question. Please understand this is not legal advise but a guide to assist you.
No they do not have to use their dash cam.
If they are recording you have to be advised that you are being recorded.
You are under arrest if they have told you that you were under arrest.
They are not required to video it.
I would suggest that you go and have your own independent test to back up tour allegations that there was no drugs.
If they take you to a station and the test is negative that is the test they have to rely on and if you are asked to go to court they have to provide you with a copy of the test.
I hope this makes sense and is of assistance, if there is nothing further
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