The summary is misleading. The person in question is Andrej Holm; the word matching algorithm did not directly lead to the search of his home and his arrest. It led to an investigation (in conjunction with his known extremist leanings); the warrants for the search and the arrest were based on his meetings and mail exchanges with the suspect in an arson case [1] (that suspect was later convicted of attempted arson and membership in a criminal organization).
That said, while there was plenty of probable cause to justify a search warrant [2] (as far as I can tell), the arrest warrant was all kinds of questionable, even considering the additional incriminating evidence that was found as the result of the search [3]. As the Federal Court of Justice noted when they vacated the arrest warrant [1], all the prosecution could prove was him having connections with the extreme left, but no evidence that he was involved in terrorist activities. And having extreme left sympathies and writing extreme left articles may be criminally stupid, but it's not a crime.
With regard to "bursting into their Berlin home", the article also does not mention that Holm had been a member of the "Wachregiment Feliks Dzierzynski" [4], an elite paramilitary regiment under the command of the Stasi. Together with Holm's undoubted connections with the extreme left, law enforcement could be excused for assuming that he may be dangerous.
The real concern is that the prosecution kept pushing even when it became increasingly clear that they caught the wrong guy (along with the actual perpetrators); thankfully, the courts would have none of it (this time).
[2] Strictly speaking, German criminal procedure law has different requirements for searches compared to US law, but there's a "probable cause"-like element, and from the looks of it, the prosecution would have had probable cause under the US standard, too.
[3] The standard for an arrest warrant is "dringender Tatverdacht", meaning that the suspect is very likely to be the perpetrator, based upon available evidence; it's a higher standard than what is necessary to prosecute, which requires only that a conviction is likely, not very likely. An additional requirement for an arrest warrant is that the suspect is either (1) likely to flee or to (2) engage in obstruction of justice or (3) has been previously convicted of serious crimes and there is substantive evidence that he or she may commit other serious crimes.
That said, while there was plenty of probable cause to justify a search warrant [2] (as far as I can tell), the arrest warrant was all kinds of questionable, even considering the additional incriminating evidence that was found as the result of the search [3]. As the Federal Court of Justice noted when they vacated the arrest warrant [1], all the prosecution could prove was him having connections with the extreme left, but no evidence that he was involved in terrorist activities. And having extreme left sympathies and writing extreme left articles may be criminally stupid, but it's not a crime.
With regard to "bursting into their Berlin home", the article also does not mention that Holm had been a member of the "Wachregiment Feliks Dzierzynski" [4], an elite paramilitary regiment under the command of the Stasi. Together with Holm's undoubted connections with the extreme left, law enforcement could be excused for assuming that he may be dangerous.
The real concern is that the prosecution kept pushing even when it became increasingly clear that they caught the wrong guy (along with the actual perpetrators); thankfully, the courts would have none of it (this time).
[1] http://juris.bundesgerichtshof.de/cgi-bin/rechtsprechung/doc... (judgement vacating the arrest warrant against Andrej Holm, in German)
[2] Strictly speaking, German criminal procedure law has different requirements for searches compared to US law, but there's a "probable cause"-like element, and from the looks of it, the prosecution would have had probable cause under the US standard, too.
[3] The standard for an arrest warrant is "dringender Tatverdacht", meaning that the suspect is very likely to be the perpetrator, based upon available evidence; it's a higher standard than what is necessary to prosecute, which requires only that a conviction is likely, not very likely. An additional requirement for an arrest warrant is that the suspect is either (1) likely to flee or to (2) engage in obstruction of justice or (3) has been previously convicted of serious crimes and there is substantive evidence that he or she may commit other serious crimes.
[4] http://en.wikipedia.org/wiki/Felix_Dzerzhinsky_Guards_Regime...