[refurb]

How can legal permanent residents be denied entry? I mean this has to be breaking So many laws, how can this be ok?

You have it wrong. The only people that can't be denied entry to the US are US citizens. When I had a Green Card it was made very clear to me that a green card does not guarantee entry to the US.

For example, if you leave the US (and have a green card) for more than 6 months the onus is on you to prove you haven't given up residency in the US.

[gdilla]

sure, but of all the people to blanketly keep out, the ones who where actually vetted, did their paperwork and followed the law seems counterproductive.