Can I modify a modify a product and sell it?

Initially, it would depend on whether the original product is protected by an unexpired patent. If the original product is patented (and unexpired), you may nevertheless sell your "modified" version of the product AS LONG AS YOUR your "modified" product does not "infringe" the original product's patent. If the original product is not protected by a patent, you may freely sell your modified product as well as the original product (as long as you do not use any trademarks/copyrights associated with the original product with your product). In addition, there is no specific percentage that a person can modify a product in order to avoid infringement. Patent infringement is determined by a complicated analysis. The analysis includes a determination of whether at least one claim in a patent literally "reads on" an accused infringer's device, product, or process, or covers the allegedly infringing device under the doctrine of equivalents. In other words, the accused infringer's product must fall under at least one of the patent claims; the claim is said to "read on" the product. If a claim does not "read on" the product, the product is not infringing upon that claim.

You should be able to modify a product and sell it if you purchased the product in the ordinary stream of commerce, unless the product, even as modified, is protected by a patent.

If you purchase a product from its manufacturer - or authorized retailer - it is yours, and you are free to use it and to re-sell it - without obligation to the manufacturer. However, if you modify the product - someone, likely the original manufacturer - might have a patent that covers your modified product. If so, you could be an infringer for making, using and selling that "new" product.

Yes, you can but you must make sure that the new product that you sell does not infringe anyone else's patent or you can be sued for infringement.

You should get specific advice about the specific product from an attorney. In general, if you buy a product from a company, you can modify and resell it. There are exceptions.

It depends upon the product. If you're modifying a common good such as PVC pipe, there shouldn't be any problem. However, if you simply put a new case on an I-phone and sell it as a paperweight, you're going to hear from Apple pretty quickly.

This is an excellent question! One threshold question is the original product protected by patents or copyrights. *COPYRIGHTS* For example - an IPhone or a smartphone using WORD. The copyright owner has rights to all derivative works. Accordingly, it will be problems with modifying these types of products and reselling them. You may be able to negotiate a license of the copyright with the copyright owner. *PATENTS* When you buy a product from an authorized distributor/dealer, the buyer has an implied license to use the product for the purpose for which it was made. So, for example, if you are building a pair of glasses with a radio built into the radio, you buy the pair of glasses from an authorized dealer and you buy the radio from an authorized dealer, and you modify the radio to combine it into the pair of glasses, neither the seller of the radio nor the seller of the pair of glasses can sue you for infringing their patents. You have bought their products from authorized distributors. They have been paid. However, there are several other issues that you will need to consider. Someone else may have patent rights for the combination of a radio and a pair of glasses and you may be infringing on this person?s patent. Also, you may be entitled to a patent for your new product. You must apply for the patent before you start selling your product. A patent search would be most useful here. I recommend that you seek the advice of counsel before moving forward. There may be some real opportunities here, and you need to proceed in the proper manner. I hope that this has been of some assistance.