Habeas doesn't require overworked criminal prosecutors to participate at all. Copyright and trademark violation can be pursued completely in civil courts. That's the innovation: removing a dependence on new anti-spam laws, uninterested public prosecutors, or dispersed private interest. Habeas creates a concentrated private interest with the motivation and means to go after fraudulent spammers privately.

Also check their FAQ: the DMCA has nothing to do with their enforcement strategy.

They're ex-MAPS people who have addressed some of the major flaws and abuses inherent in the MAPS approach.

Your "downside" scenario seems vanishingly unlikely to me: they become *the* single dominant mail-guarantor, users become locked into ISPs that kill almost everything that doesn't have SWE-marks, Habeas renegs on its initial promises, ISPs still stick with Habeas despite this change, there are no competitive email providers or mail-guarantors... then, and only then, could some future "evil Habeas" significantly impinge on others' legit communication. (And at that point, lots of competitive/legal countermeasures would be available against an abusive owner of the SWE-marks. I also believe there are similar ways to achieve the same benefits not covered by their pending patent.)

Lets not squint and speculate to imagine oppression, coming from a currently tiny startup, at some imagined point in the distant future -- when there's plenty of actual oppression, by truly large and powerful entities, in the here-and-now.