Of course, US DM can pretty much do what they want & when they want, but there does seem to be some growing pressure on US programs to give notice. I actually thought I read on FT somewhere that some regulator in the US was looking at regulating this but really not worth trolling FT to find out. Perhaps more significantly there has been somewhat of a swelling of popular criticism against this practice of not giving notice in recent times, and the airlines have taken note and "promised" to give more notice when/if they can. What that will translate to is anyones guess!