Sony now is embroiled in a controversy over a patent limiting video game use. The patent would prevent Sony PlayStations from playing used, rented or borrowed video games. This would cripple the First Sale Doctrine that consumers own physical goods they purchase and have the right to use or transfer such goods.

It is highly unlikely that Sony would actually use such technology due to outright consumer rejection. Typically such patents stake out territory so others can't claim it and may be useful for licensing.

The reason this is significant is the PR lesson. Sony is the same wonderful company that brought us spyware on a music CD. The company created great mistrust among the public. The patent would have attracted little notice, had Sony not damaged its reputation with the spyware mess.