Why can't you rebrand a product? You bought it, you own it, you can resell it.
This case is much more complicated however. It's two business partners who had a falling out and both tried to put each other out of business. The marketing guy kept their own brand and customer base while the tech guy tried to rebrand and sell his products on his own. The marketing guy hired an engineer to make a new product that does the same function. The tech guy accuses him of copying his technology.
http://robertfleminglawyers.com/pdf/2012_BCSC_1490_Equustek_...