Prepositions

[Allen165]

"Robert C. Cumbow is a shareholder with Graham & Dunn, Seattle, where he counsels clients in beverage, food, communications, entertainment, and other businesses on trademark, copyright, advertising, media, and alcoholic beverage law."

The above sentence was written by Robert C. Cumbow, who's a lawyer and grammarian. I'm wondering why he wrote he wrote "in" before "beverage...." and then "on" before "trademark...." I don't think it's a typo because the same sentence appears at the bottom of all the articles written by him.

Thanks a lot!

[riquecohen]

He counsels clients who are engaged in various types of businesses on various types of laws.
The sentence is written correctly.

[Pedroski]

I would read it: in (the areas of) ...... on (matters of). I don't think you could swap them around, because he would then give advice about beverage etc.