I'm trying to find out if this Patent No. USD513117 S1 is still valid. How can I find out for sure?
According to Google Patents, the owner paid the most recent maintenance fee so the patent is still in effect. Whether or not the patent should be invalidated (ie, whether or not it should have been granted in the first place) is a separate question and would depend on whether there is any litigation that ever invalidated the patent. Google doesn't show any mention of litigation involving this patent, so it would likely still be valid in the eyes of the PTO.