One day in late November, a surprise caller turned up at PerrigoCo Plc's Dublin headquarters, close to the city's so-calledGoogletown neighborhood.

Informed that the drug maker's CFO Ron Winowiecki wasn't around,the visitor dropped off a letter at its second-floor office in theTreasury Building, famed for “Aspiration,” the sculpture of a nakedwoman scaling its exterior walls. Inside the envelope was a taxdemand for a whopping 1.6 billion euros (US$1.8 billion), thesecond-largest in Irish history, according to an account of theepisode given to the government.

Weeks later, Perrigo revealed the assessment to shockedinvestors, sending its shares plunging 29 percent. That cameshortly after Analog Devices Inc. told its shareholders the companyfaces a much smaller, but potentially significant, tax battle ofits own with Ireland. Taken together, the cases may signal thatIreland is taking a tougher line with U.S. companies using thenation to lower its taxes and as a gateway to Europe.