Ways to be 100% sure that a controlled substance prescription is legitimate?

I have 3 different scenarios: Patient A has been getting hydrocodone/apap 10-325mg #150, phentermine 37.5 mg #30, promethazine /codeine syrup 473 ml, and Soma 350mg #90 every single month, with a diagnosis of "chronic pain and emphysema" for the past 3+ years, verified by her pain-clinic doctor, who writes all four scripts for her every month. She doesn't seem to have any symptoms of emphysema as her lung capacity is quite good when she shouted, screamed and threatened us for an entire 8... Ways to be 100% sure that a controlled substance prescription is legitimate?
Source: Student Doctor Network - Category: Universities & Medical Training Authors: Source Type: forums