New 35 U.S.C. §298 provides:

The failure of an infringer to obtain the advice of counsel with respect to any allegedly infringed patent, or the failure of the infringer to present such advice to the court or jury, may not be used to prove that the accused infringer willfully infringed the patent or that the infringer intended to induce infringement of the patent.

There is no specific effective date for this section, so it takes effect on September 16, 2012.

The statute merely prevents the failure to obtain an opinion of counsel or the failure to present an opinion of counsel to prove willful infrnigement or to prove inducement.  It does not prevent the introduction for other purposes, for example to show that increased damages or attorneys fees should be awarded after a finding of willfulness has been made.  Having a favorable opinion of counsel can also be valuable, because it can be introduced to show the absense of willfulness or the absence of inducement.  Furthermore the process of obtaining the opinion may result in changes that reduce the risk of an infringement claim in the first place.