What is my nation?

He stood at the Woodside bar last Friday night, looking up at the television. He looked like a man who'd been kicked in the chest. The blood went from his cheeks. His hands shook. He bit the inside of his lip. He asked the bartender to turn the news up. He wasn't quite sure if he had heard correctly. The report was just 30 seconds long, but often a half minute is enough to know that the nightmare we are enduring is, in fact, our own life.

Nearly everyone in the working-class bar was Irish and was concerned with the news. They were ready to celebrate. When it came it was like watching the air go out of old tyres. A small stunned silence and then a ripple around the room. The US Senate had been suspended without making a decision on the new McCain-Kennedy immigration laws.

"What ish my nation?" asks Captain Macmorris in Henry V, in what is possibly the earliest dramatic expression of Ireland's identity crisis. Of course, it's no longer just Ireland's crisis but a general one that reaches all the way from New York to Drumshanbo to Krakow to Sydney. Why should we apologise in choosing where we want to live? Who is to say what is a nation now? Why should we live our lives purely by postal addresses? Why is it that our minds have to be punched into a passport and then shut away in a little drawer?

The man at the bar was from Leitrim. He left Ireland 14 years ago, went to New York, worked in hot-roofing and became a carpenter, working in the theatre industry, props, backdrops, scenery. He married his childhood sweetheart, a girl from Laois, and both of them got on with their American lives. He accepted the fact that he didn't have a visa or a green card. His father, back in Carrick-on-Shannon, died a long and complicated death. But the Leitrim man couldn't return home – to go back was to lose whatever life he had left for in the first place. He sat in a bar on Katonah Avenue and wept his eyes out.

When his mother passed on just six months later he couldn't stand the notion of not returning. This time he drove to Canada, took a flight across, attended her wake, carried her body out the front door. He felt Irish again, and, being Irish, was therefore ready to leave. He got back into America by hiding in the back of a fruit truck. He settled back in New York, continued his life, had two children, paid his taxes, thought about how his life had been borrowed by paperwork, walled in with documentation, but like most Irish people in the States he thought he could slide by without the formal bureaucratic nod.

Then the towers fell. Along with them went an amount of empathy. Immigration was confused with terrorism by cheap politicians who were interested in putting defence-contract money into their own pockets. A crackdown began. Arrests were made. Fingerprints were asked for. Drivers' licenses were scrutinised. Talk began of criminal penalties for "unlawful presence." Not having a visa – which was once just a civil violation – would then be turned into a crime.

The Leitrim man knew that he could be arrested, put in jail, deported, separated from his children. He heard stories about cages. This was not how he wanted to live. This was not what he had left for. It was not only his life that was on the line, but his wife's too, and his kids, and in a strange way 11 million others who were illegal in the United States, amongst them 50,000 Irish-born. They were all looking over their shoulders. They ran scared. They became afraid even to enroll their children in schools. Increasingly they were being held hostage to their pasts. Going "home" was not an option – not when a whole life was built into a new home. And staying didn't seem a possibility either.

And then last week they looked up at the TV screens only to see politicians once again blithely ignore the human consequences of their decisions. What was at stake seemed decent and human and right. The undocumented workers who had been in the US a number of years would pay a fine of $2,000 and then embrace what they felt was democratic – the possibility of participating in the soil they stand on.

But late on Friday afternoon the measure fizzled out. The politicians went on holiday, as politician do. The issue is supposed to be rekindled when the Senate returns in two weeks, but in the New York bar on Friday night there was an overwhelming sense that a lot of damage had been done. The oxygen felt like it had gone from the air.

"Who cares?" goes the refrain of the anti-immigrant lobby. "They're illegal, they should go home."

But what is home anymore? Who belongs? It is – for the Irish government as well as that of the US – a crisis of belonging. For those of us who need reminding, Shakespeare put this into the mouth of Macmorris: "What ish my nation? … Ish a villain, and a basterd and a knave and a rascal."

Colum McCann's column for Round Midnight with Donal O'Herilhy on RTÉ Radio 1 (11.40pm) goes out every Tuesday night