• The unexcused failure to take action in a timely manner (in lay terms, sitting on your hands).

• Having discovered an infringement, a patentee must take action (file suit) with reasonable promptness.

• If the patentee fails to so act, and the delay causes material prejudice to the (alleged) infringer, the patentee may be barred from recovery of any damages for past acts of infringement—those occurring prior to the filing of the suit.

• The patentee may, nonetheless, obtain an injunction barring further infringement of the patent(s)-in-suit.