It appears that the first thing to due when you get sued for patent infringement is to say its an invalid patent.

The key issue in that case - the question of what constitutes an "obvious" and, hence, invalid patent - could have a bearing on the Plavix patent.

The Tandy Corporation filed an antitrust suit last month accusing Texas Instruments of seeking excessive royalties for invalid patents.

Dissatisfied with the supply of generic drugs, Congress passed the Hatch-Waxman act in 1984 to encourage manufacturers to challenge weak or invalid patents on brand-name drugs.

They are concerned that invalid patents will issue and that this will lead to patent trolls inhibiting new product introductions by demanding excessive license fees for these questionable patents.

Kathleen D. Jaeger, president of the Generic Pharmaceutical Association, welcomed passage of the bill, saying it would help generic drug companies challenge "weak or invalid patents" on brand-name medicines.

The suit, filed in Federal District Court in San Francisco, accuses Texas Instruments of forcing personal computer manufacturers like Tandy and Grid to make excessive license payments for invalid patents.

Subsequently in 2007, in United States Federal Court in Jackson, Mississippi, Prime Table Games proved that the 1999 PGIC litigation was based on fraudulent and invalid patents.

Apple can ask the ITC to review the infringement decision in light of the USPTO's invalidation of those patent claims as ipso facto an invalid patent claim cannot be infringed.