Legal Question in Business Law in California

You'd run the risk of a civil lawsuit. Without much more information, I'd not be able to give you any idea how great a risk, but just as a general matter, manufacturers of branded products do have some continuing rights in their products, even after a sale to a consumer. In the example of the advertising pens you gave, please note that (a) the pens are made and sold with the thought in mind that some buyer advertising will be added to them; (b) the buyers generally will have an agreement of some sort with the manufacturer; and (c) the advertising added to the pens is (usually, at least) in addition to the manufacturer's name, and doesn't obliterate it.

As a Torrance attorney I'll answer this. Don't do it. You need a private label product if want to label it, otherwise its a big problem. Trying to pass off the item as your own when its not a private label you may violate both federal trademark and state unfair competition laws. Its called reverse passing off and you're taking credit essentially for someone else's work, design, etc. and you're not allowed under the law to do that. Note if your supply found out what you were doing they would cut you off in a heartbeat.

What you need to get is a good manufactured for private labeling. For instance there are private label items like as mentioned pens, and the most common I can think of which is milk. Notice a grocery store selling their own private label milk (like Ralph's Milk, Von's Milk. Albertson's Milk, etc). Don't relabel and start selling it as your own.

*edit* Note if your *supplier* found out what you were doing they would cut you off in a heartbeat.