I personally have always thought so, especially since I’ve seen heraldry being used as trademarks enough times, on things from bottles of wine to entire restaurants.
But in an on-line article dated December 16, 2011, English attorney Paul Bicknell gives us a more definitive (and relatively short) answer, at least from the view of English law. It’s a nice, short, easy to read and understand little article, though he could have used another proofreader. “Court o the Lord Lyn” should, of course, be Court of the Lord Lyon.
And, of course, it has no application on this side of the Atlantic; the United States is less restrictive about the use of armorial ensigns as trademarks, and Canada has its own laws and heraldic authority to consult with.
If you’d like to go read what Mr. Bicknell has to say, his article can be found at http://www.lawdit.co.uk/reading_room/room/view_article.asp?name=../articles/13535-coats-of-arms-trade-marks.htm