Q&A: Who is Obama helping?

So what actions did Obama take on immigration on Thursday? He announced executive orders allowing up to five million illegal immigrants to remain in the United States by protecting them from deportation for three years. That's about two in every five undocumented migrants, of whom there are an estimated 11.4 million in the country.

How is he doing this? Obama is shielding them from deportation by ordering immigration enforcement agents to focus on security at the border with Mexico (over which most illegal immigrants enter); criminals; and migrants who arrived within the past five years, rather than the undocumented who have been in the US for more than five years.

Which immigrants is he helping exactly? Most of the migrants who will benefit – about four million – are undocumented parents of US-born citizen children or legal permanent residents. They must have been in the US for at least five years to qualify and undergo a criminal background check and pay their up-to-date taxes. Migrants can start applying next spring.

Another million are affected by other measures, including the extension of a 2012 measure Obama introduced allowing migrants brought to the US illegally as children to remain in the country.

How many undocumented Irish will this help? It's not clear how many will be affected. Nobody really knows the exact number of undocumented Irish in the US. The Irish Government estimates that there are about 50,000 and Irish immigration activists expect the president's orders to benefit thousands.

Will it solve the long-running problem of people being unable to return to Ireland for important family occasions such as funerals? It will for those qualifying for legal status, but it's not clear yet how easy or flexible it will be for them to travel freely to and from Ireland. The devil will be in the detail and at present the small print needs further explaining.

The White House said the department of homeland security, the government agency that enforces immigration policy, will relax measures that separate family members whose applications for legal permanent status are pending. They will do this by extending waivers for certain violations, which will allow them to leave and return to the US.

To ensure individuals with lawful status can travel to their countries of origin, the department will “clarify its guidance to provide greater assurance to individuals with a pending lawful permanent resident application or certain temporary status permission to travel abroad with advance permission (‘parole’)”, the White House said.

Qualifying migrants can apply for a waiver, meaning they won't face long-term bars from re-entering the US returning from Ireland in cases of "extreme hardship", but it still has to be spelt out what that means in practice.

At present, if someone has lived illegally in the US for less than a year, they can be barred from re-entry for three years after leaving the country and for 10 years if living illegally for longer than that.

"We expect to see some expansion of who benefits from the waiver of the three- and 10ten-year bar," said a senior Obama administration official.

So is Obama making five million undocumented people US citizens? No – he doesn't have that authority. He's only telling them that he is not going to deport them and that the measures are also only temporary. The next president can reverse these measures with executive orders of their own in 2017.

You keep mentioning "executive orders" – what are they? Under his constitutional authority, the president can, as head of the executive branch of US government, issue orders to federal departments and other government workers to act in certain ways. Executive orders allow presidents to bypass opposition in Congress.

So are these immigration orders legal? Obama says they are. Most Republican and some Democrats object, with Republicans claiming that they are illegal and that he is exceeding his powers and acting like "Emperor Obama". Some are threatening to block funding for his actions, to sue him and even impeach him.

Does he need the support of Congress to do more? Yes, there are limits to his powers to fix a "broken" immigration system and to legalise migrants permanently or put them on a path to citizenship, which was proposed under a Bill that passed the Senate last year but stalled in the Republican-controlled House of Representatives.

Finding consensus with Republicans will be difficult, given how his go-it-alone actions have riled them. The numbers are also against him: Republicans won back the Senate in this month's mid-term elections which will give them majorities in both houses of Congress from January, increasing the bitter divisions in Washington and enhancing the Republicans' capacity to undermine him.