Ritically discuss why a clinical trial protocol is essential in clinical trials

Question: Critically discuss why a clinical trial protocol is essential in clinical trials.

Notes:

There are many different aspects you can cover in this title; if you wish to approach if from a general perspective, or concentrate on a particular area of interest to you, either is acceptable.

If you wish, you can use caffeine practical as an example, or any other examples which are of interest to you.