Freedom-to-operate Analysis

I would add one comment to those already posted -- your FTO search should include not only issued patents, but published patent applications. US PTO publishes US patent applications 18 months after filing. These are not granted as yet, but are pending. You can't know for certain that they will issue, or issue as published (inventor may need to amend claims before allowance, which will then differ from the 18 month draft). But, it can give you some insight as to whether or not you may face a future infringement suit. WIPO and US also publish pending International Applications (filed through WIPO under the Patent Cooperation Treaty), so if you want to operate in a country other than the US, you may want to search published WIPO international applications, as well of course any natively filed applications in particular foreign countries you wish to operate in (i.e., Germany, which is a foreign country relative to US patent law). In the US, any application pending less than 18 months is not yet published, so there is still a window for surprise that a patent may show up after you search. But searching only issued patents leaves some exposure to those pending as well.