PATRICIA SABGA:

Pretending to shift activities offshore is also the main critique of another legal tactic known as an inversion. That's when an American company changes its corporate citizenship by acquiring a firm based in a lower tax country or jurisdiction. Since the 1980s, more than 50 American companies have pulled this off…with 25 such deals in the past five years alone.

Samsonite, the century-old luggage maker, moved its tax address from Massachusetts to Luxembourg, where the corporate tax rate is 19 percent. Restaurant Brands International, parent of fast-food chain Burger King, relocated its headquarters from Florida to Canada, where the corporate tax rate is 15 percent. But the number one destination for tax inversions is Ireland where at 12-and-half-percent, the corporate tax rate is nearly two-thirds lower than the U.S.

The biggest company to change its tax address from the United States to Ireland is medical device maker Medtronic, which still maintains a hefty presence in its native Minnesota.

Medtronic's operational headquarters and its top executives are in the United States. But its official headquarters is here, in Dublin, Ireland, in that building behind me. That change of address was engineered two years ago, when Medtronic bought Covidian, an Irish-based medical device maker.

This modest building in Dublin may be Medtronic's global headquarters, but the company employs around 4-thousand people in Ireland, compared to more than 43-thousand in the United States.