Five years after being pegged a monopolist, Microsoft is coming under scrutiny for efforts to license its proprietary technology in accordance with antitrust legal demands from U.S. and European regulators.

The Microsoft Communications Protocol Program (MCPP) was envisioned as a way to encourage competition and promote interoperability between Microsoft’s products and Unix, Linux and open source applications. Whether the licensing program has worked as planned is a topic of hot debate, and the U.S. District Court in Washington plans to take up the subject for review on Sept 11.

Microsoft is calling the licensing program a success, with more than 40 companies, most undisclosed, licensing more than 200 Microsoft protocols for server, storage and security services. But six states and many open source advocates are deeming the MCPP licensing effort a failure in terms of promoting competition and interoperability.

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“MCPP licenses are simply not a viable option for suppliers of open source products – the principal alternative to Microsoft in the server market,” states California’s assistant attorney general Kathleen Foote in an Aug. 30 legal filing the state made on behalf of California and five other states calling themselves the California Group. “These companies cannot utilize MCPP licenses because of their royalty provisions and other restrictions on the use of intellectual property.”

That view is echoed by open source advocate Jeremy Allison, lead software developer at SAMBA, the open source project that provides freely available code used for interoperability between Linux/Unix servers and Windows-based clients.

“We read the license,” says Allison about MCPP. “It’s impossible to release open source implementations of the product. You have to keep it secret. This defeats the whole idea of open source.”