I think its unlikely that anyone's forgotten the mess — and the protests, and the heartbreak — surrounding Donald Trump's first attempt at a travel ban. Now, just over a month later, he's taking another stab at it. It's natural, though, that the question of whether the new travel ban is legal would arise; after all, the first one died after it failed to pass constitutional muster. Now, however, the Trump administration has re-tooled a few of the most damning aspects of the original ban — and the question still remains.
From the perspective of the ban's opponents, the new version has relatively few changes. They've removed Iraq from the list of countries affected, saying that Iraq is an important ally in the fight against ISIS that has certain vetting measures. The order also contains a few new exceptions for people from the banned countries, including legal permanent residents, embassy workers, and those who have already received asylum of refugee status.
These are some of the issues that state attorney generals found to grab onto with the first ban, using the claim of "state standing" — meaning that the states had grounds to sue the federal government over the ban because of the damage it caused to their residents.
The main goal of the changes, rather than helping the American people, is to help the travel ban pass through the courts more easily. Being what it is, though, there's no way that the administration could have written it to both retain their goal and make it completely, unquestionably legal.
The new travel ban still offers no justification for the six countries on the list, and the fact that the administration could point to no justification for banning those exact countries was one of the main factors that brought the first one down. Since the release of the first ban, multiple reports have come from the various national security agencies saying that screening people from particular countries isn't a great way to fight terrorism. If the administration can't justify the new ban on national security grounds either — which it will be hard-pressed to do, given the limited nature of the changes — then reports like that could easily contribute to its derailment.
Of course, there's a good case to be made for the argument that the travel ban's main rationale isn't national security. Greg Sargent at the Washington Post reports that it's a part of a Steve Bannon-Stephen Miller plan to demographically reshape the country — excluding people from the six countries in the ban. Is that legal? Read in plain language, it seems like discrimination based on place of birth — which is legal. However, it is possible that the administration has couched the language in such a way that it will get through the courts unscathed.
Other changes include the removal of the clause regarding religious minorities, which stated that the outright ban on refugees would not necessarily apply to those of a different religion. As that was an easy target for those wanting to say that the ban discriminated based on religion (by banning Muslims and leaving things more open for Christians and other religious minorities), this is another clear move to make it more easily defensible.
The new travel ban will go into effect on March 16, which gives the relevant authorities more time to make their plans and avoid the confusion that surrounded the first one. However, the legal cases against it from liberal grounds will undoubtedly be prepared well before then. They will certainly find something on which to base what will certainly be a multitude of cases, but ultimately it will be up to the courts to decide whether the ban can legally be enforced.