Ensnarement 101: Anatomy Of An Uncommon Patent Defense

By Ryan Davis (October 24, 2017, 2:04 PM EDT) -- A recent Federal Circuit decision clearing Boston Scientific Corp. in a $200 million patent case drew attention to the rarely invoked ensnarement defense to infringement. Here's a primer on how the defense works and why attorneys say accused infringers should consider using it more often.

In a ruling last month, the appeals court upheld a judge's decision that the ensnarement defense shielded Boston Scientific from liability in a case where a doctor alleged the company's Express coronary stent is covered by his patent.

Ensnarement bars patent owners from asserting an infringement theory under the doctrine of equivalents that encompasses, or "ensnares,"...

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