An issue in local practice under the Patent Local Rules is the relationship between contentions, whether they be infringement or invalidity, and the reports of experts who will present those contentions to a jury. The issue of when there is "good cause" to amend contentions under P.R. 3-6 gets a great deal of attention, but in recent opinions, the Eastern District has provided some guidance on the significantly rarer issue of when an expert's report impermissibly expands the contentions previously disclosed under Patent Rules 3-1 and 3-2 or 3-3 and 3-4, as the case may be.
First of all, the legal standards in this area are clear. Expert reports may not introduce theories not previously set forth in contentions, but the scope of the two is not the same. In referring to infringement contentions, for example, the Court has told us that they need not disclose "specific evidence nor do they require plaintiff to prove its infringement case". But on the other hand, expert reports must include a complete statement of the expert's opinions, the basis and reasons for them, and any data or other information considered when forming them. See FRCP 26(a)(2)(B).
The report cannot accuse new products nor advance new theories - that much is clear. But it appears that it can refer to previously un-accused products in relation to accused products - it just can't add new products to those it identified in as accused in its contentions. And it can use language not in the contentions, so long as the concept has been previously disclosed. The test for when new language is permissible is whether the contentions provided "adequate notice" of the theories the report contains.
MCS3164; MCS1800; MCS 1365