Cadence has brought a suit against Berkeley Design Automation for, as far as I can see, integrating their AFS circuit simulator with the Virtuoso Analog Design Environment (ADE) without using the (licensed) Oasis product. Since BDA is (actually was) a member of the Cadence Connections program, they have to abide by the contract which only allows them to create interfaces that their Connections legal contract allows. In particular "Member is not licensed to develop any interface to or translator for a Cadence product other than those specifically identified in exhibit x".
Cadence does allow 3rd party simulators to be used with ADE but only if (a) the end-user has a license to Oasis, Cadence's integration product and (b) the integration is done through Oasis. According to the complaint, BDA have circumvented commands within Virtuoso that require the Oasis license and their integration is not through Oasis, as a result of which end-users could use AFS with ADE without obtaining an Oasis license.
Cadence alleges that this is not just a breach of contract but is also a violation of the digital millennium copyright act (DMCA) and are seeking damages from BDA for loss of Oasis license fees, lost profits and so on. And, obviously, an injunction to prevent BDA from integrating AFS in this way.
Per the complaint, this came to light in mid-2012 when a Cadence engineer was trying to help a common customer troubleshoot ADE/AFS issues, and the customer showed them the BDA AFS installation guide which stated that "the Oasis integration is deprecated. BDA strongly discourages users from choosing this method." The installation guide dates from 2010.
Of course I have no idea of the details of what or how BDA have implemented their integration, or whether most customers using the two products together did or did not have an Oasis license anyway although Cadence believes they did not.
According to a Cadence spokesperson, "Over many months before filing this lawsuit, Cadence made repeated proposals to work with BDA’s management to rectify this situation. Cadence was, however, unable to persuade BDA to comply with its contractual obligations under the Cadence Connections Program. Consequently, Cadence did not renew BDA’s participation in the Connections Program. Cadence is also seeking injunctive relief and damages for lost OASIS license fees, among other relief."
Obviously it goes without saying that neither I, nor DAC, nor MP Associates, have any position on this matter.