At the very start of the textbook Fundamentals of Clinical Trials the authors make a distinction between clinical trials — comparing two or more different interventions — and clinical studies, which merely describe an intervention without comparing it to anything. So, there can be no such thing as a “Phase 1 trial”, since they typically involve a single drug at different doses and schedules. The only true trials, according to the authors, would fall under Phase 3, or Phase 2b at the earliest.
This is stupid, misleading, and not at all how the words “trial” and “study” are used by anyone else, including the biggest and most important drug regulatory agency in the world. There are many such pointless exercises of professorial power in medicine, including my favorite: whether the correct pronunciation of “+” in “7+3” is “plus” or “and”. They amount to nothing more than purity tests that award the wielders of the right language a false sense of precision. As Nassim Taleb wrote, nitpicking is the enemy of thought.
The rest of the book is good enough, but more on that later.