Crossroads Systems Inc. (CRDS), the patent licensing company that is partnering with Fortress Investment Group to sell its non-core patent portfolio, as expected appealed the Patent Trial and Appeal Board’s rulings in four inter partes reviews invalidating most of the claims of three patents the company considers fundamental to secure and efficient access to network storage systems.

Austin, Texas-based Crossroads is asking the Court of Appeals for the Federal Circuit to reverse a number of PTAB rulings in IPRs handed down on Jan. 29 and March 17.

The PTAB on Jan. 29 affirmed the validity of claims in IPR 2014-01197, but ruled that the claims in IPR 2014-01226 were unpatentable. The IPRs were filed by Cisco Systems, Quantum Corp., Oracle Corp. and Dot Hill Systems Corp.

Another final ruling in a related IPR petition filed by NetApp, Oracle and Dot Hill found the claims of the patent were not unpatentable.

The IPRs being appealed today are 2014-01226, 2014-01463, 2014-01544, along with the IPRs joined to those proceedings 2014-00825, 2014-00854, and 2014-00852, respectively.

The patents at issue in the rulings are U.S. Patent Nos. 6,425,035, 7,051,147, and 7,934,041.

The ‘147 and ‘035 patents also are at issue in enforcement actions filed by Crossroads against Cisco, Quantum, Oracle and Dot Hill.

Last month, Crossroads, which is run by CEO Richard Coleman Jr., made good on its pledge to appeal the results of the first set of IPRs, in which the PTAB also found the patents unpatentable.

Crossroads has said the issues on appeal include the PTAB’s application and use of the broadest reasonable interpretation standard, claim construction, determination of unpatentability of claims 1-39 of the ‘147 patent under 35 U.S.C. Section 103, any finding or determination supporting or related to those issues, as well as all other issues decided adversely to Crossroads in any orders, decisions, rulings, and opinions.

The different claims constructions standards used by PTAB and the district courts is controversial and some patent owners say has led to the improper invalidation of many patents.

Last week, Fortress, whose IP practice is run by Eran Zur, agreed to partner with Crossroads to sell the struggling licensing company’s non-core ‘972 patent portfolio.

Fortress and Crossroads signed an agreement with AQUA Licensing LLC to market and sell the portfolio, which consists of 138 patents and pending patents. San Francisco-based AQUA Licensing is run by Mark McMillan, Steve Smyski and Peter Savich.

Crossroads said it previously commissioned two independent studies of the portfolio in 2013 and 2014. Even so, the company said it couldn’t provide assurance regarding the timing or value of a transaction, or even if one will occur.

In addition, Crossroads also last week announced the sale of its product business and all related assets to Canada-based StrongBox Data Solutions Inc. for $1.85 million in cash.

Fortress had previously provided financing to Crossroads, which was repaid last fall when Techquity Capital Management provided $10 million in litigation financing.

Shares of Crossroads fell 2.88 cents, or 12%, to 21 cents on Thursday, March 31.. They’ve traded between 15 cents and $2.65 over the past year.

—To reach the reporter responsible for this story, please contact Dan Lonkevich at 707 318-7899 or at