This is the federalists' revenge – the provision that allows like-minded states to forge ahead with deeper integration, separately from the less enthusiastic states.
Article III-324 states that it is "enhanced cooperation" is open to all Member States and, once certain conditions are satisfied, authorisation to proceed is granted by the Council acting unanimously. While the Council and Commission are required to encourage maximum participation, unlike the Nice and Amsterdam Treaties, there is no minimum number of countries set for a co-operative project.
In the infamous Article III-328 we then have the mind-boggling statement that:
"Where a provision of the Constitution which may be applied in the context of enhanced cooperation stipulates that the Council shall act unanimously, the Council, acting unanimously in accordance with the arrangements laid down in Article I-43(3), may decide to act by qualified majority."
I am "reliably" informed that this means that the "inner core" of participating states can run their affairs under QMV, while others invoke unanimity rules. This may be the case, although that is not exactly what the Article says. Put it down to bad drafting and possibly the surfeit of Guinness consumed by the Irish presidency. Nevertheless, this provision does not apply to decisions having military or defence implications.
The upshot of all this, of course, is that we end up with a "multi-speed" Europe with the Europhile claiming that non-participating states will be "left behind" - as if that was a bad thing. Personally, if I saw a group rushing over a cliff to certain destruction, I would be very glad to be left behind.