is it fair to say that the most important thing to note is whether a mark is 'inherently distinctive' or not?
Those are the easy ones. A term like "Xerox" is inherently distinctive, since it is an invented word having no other meaning than as a reference to that company.
There's also something about providing (or not providing) 'proof of acquired distinctiveness,' and wondering what forms of proofs would they be ?
It depends on the circumstances. The point is whether a term that is descriptive of the goods/services has become associated in the minds of relevant consumers such that it functions in the marketplace as an indication associated with a single source.
Take "American Airlines" - they're American and they are an Airline. The thing is, they've been doing it since 1939 and everyone knows that the term "American Airlines" means a particular carrier.
Same story with Coca-Cola - the original formulation was made with extracts of coca and cola. But they've been at it for more than 100 years, and everyone knows who they are.
Another one would be "International Business Machines". They don't come more descriptive than that, but only a fool would think that is anything other than a reference to IBM.
There is no fixed rule for "whether a mark has acquired distinctiveness", because whether it has or not is going to depend on whether evidence shows that people recognize it has a mark. A kind of threshold standard in the US is whether the mark has been used (a) continuously, (b) substantially exclusively, and (c) for at least five years, in commerce in the US.
In US trademark registrations, you'll often see the notation "2(f)" in the trademark record. Those registrations were allowed upon a showing of acquired distinctiveness, and if you dig into the file (under the "TSDR" button), you'll find whatever it is they had to show. Sometimes, all that is required is an oath stating the three factors I mentioned above. Sometimes there will be an evidentiary showing of such things as:
- amounts spent on advertising
- press mentions
- volume of sales relative to the market
...and other types of evidence, depending on what sort of goods/services are involved, relevant to the factual question "Is this mark considered by consumers to distinctively refer to the goods/services of this entity or not?" - i.e. Does it function as a trademark to distinguish the goods/services of this entity from its competitors?
Any other case study resources out there other than these by Wikipedia?
I'm sure there are lots of introductory books and study guides on trademarks. I've been at this since 1992, so nothing in particular leaps to mind.