He argues that United published a set of benefits in 2011 which induced members of the program to fly that year in exchange for benefits in 2012. But after members had done most of that flying, United reneged on the deal.
The elimination of economy plus at booking (making it subject to availability at check-in only) for 25,000 mile flyers was announced in September 2011.
I have always said that I believed the right thing to do is to announce substantive changes at the beginning of a year to take place the following year. Anything less is duplicitous.
I am not sure, however, that it is actionable.
Incidentally, the individual seeking to create a class action also sued Southwest when they began enforcing expiration dates on their inflight drink coupons.