"I'm known for my sense of irony. But even I would not have come to think of putting a statue of liberty in New York Harbor," Irish Nobel Prize winner of Literature George Bernard Shaw once said. But, as far as we know, he got away with this sharp-tongued comment when trying to enter US territory, a comment that implicitly made fun of the US' idea of liberty.

But maybe he was only left alone because in the early 20th century, border officials did not yet have access to the vast amount of data about people desiring to cross into their countries as they do today. Today, every visitor seems transparent; and harmless but remarks are often interpreted as evil intentions. Shaw's fellow countryman just experienced that.

US Homeland security strike

The young Irishman was denied entry by the US homeland security agency DHS at Los Angeles airport. The reason: an ironic remark on Twitter. The sender insists he wasn't even targeting the US. On the contrary, he wanted to tell his followers that he was going to "party to the extreme in LA," and he described it by saying that "digging out Marilyn Monroe" and "destroying America" were part of his plan. But immigration officers didn't care much about his sense of humor. He spent 12 hours detained in a cell.

"I can only advise against such remarks, even if you're sure you're being ironic," said Klaus Lodigkeit, a Hamburg-based IT law specialist. "Americans store almost all our phonecalls, they store a lot online, and make backup copies. And if they search for a name or a nickname online and find such posts they can link to a certain person then you represent a danger for the security of the United States. So be careful."

Cheeky teenager

But offhand and ironic remarks online can also be misinterpreted outside of airports' immigration zones. Just before the verdict for security guard George Zimmerman was announced, the killer of black teenager Trayvon Martin, a 15-year-old in the small town of Zion in Illinois posted a comment online. If Zimmerman was acquitted, he wrote, he would shoot dead every single person in Zion and then also be acquitted of charges.

A short while later, local police detained the teenager. After an examination, the officers were convinced he didn't constitute a threat. "He doesn't own any weapons and doesn't have access to any either," a police report said.

Crazy or just foolish?

18-year-old US citizen Justin Carter wasn't that lucky. According to his parents, he had a fight with other users while playing a fantasy role-playing game online. When the users then wrote on Facebook that he was "a lunatic, crazy, and off his head," Carter replied: "Yeah, sure I'm a total mess, I will go and shoot children at a school and eat their beating hearts."

He must have instantly realized that remarks like that are often misunderstood. He quickly added a ‘LOL' [‘Laughing out loud'] and a ‘JK' [‘Just Kidding']. But it didn't help: He spent several months in prison because of that comment on Facebook. He has been released on bail.

"If you publish a concrete threat to life or physical condition online, the threat itself constitutes a criminal offence," according to IT legal expert Lodigkeit. "It's enough to be convicted. And you're remanded in custody while investigations are conducted because you're considered a flight risk."

But does that give security agencies in Germany and the US the right to spy on private communication? "No," said Mario Tants, spokesman for online freedom advocates the Pirate party in the German state of Schleswig-Holstein. "In the cases we've talked about, security authorities in the US didn't screen private communication. Instead, what happened was that somebody who knew the respective perpetrator or potential perpetrator gave them hints. And if a real person gives a real hint, then security agencies are obliged to examine what's going on."

'NSA spy protection league'

The latest case from Germany is slightly more confusing in comparison. 28-year-old Daniel Bangert invited others on facebook to join him on a "Walk to the Dagger complex." It's a US-American installation near Darmstadt in the German state of Hesse, where the NSA is said to have underground offices. Bangert clearly used an ironic tone, calling his group the "NSA spy protection league," inviting others to "explore and observe."

But the US military police in Germany apparently don't share Bangert's sense of humor. The Americans informed German security agencies who then visited the young man early in the morning and interrogated him. State security were also involved and asked Bangert questions about his "political leanings," as he put it.

"That's exactly what we're critical of," said Mario Tants from the Pirates' party. "In future, any citizen writing anything anywhere has to expect a visit by the police or state protection. That's the problem in surveillance states, and we're actually effectively already there."