Germany's Constitutional Court began hearings this week on the use of new police surveillance software in the states of Hesse and Hamburg, which both controversially changed policing laws to accommodate the new software.

Though "Hessendata," adapted from the Gotham program developed by the US company Palantir, is not yet in use in Hamburg, it is already being used extensively by the Hesse police since 2017.

The constitutional complaint was brought to Germany's top court in Karlsruhe by the German Society for Civil Rights (GFF), representing 11 plaintiffs, including the prominent Frankfurt-based lawyer Seda Basay-Yildiz, who argued that it can be used to search vast amounts of social media data to create profiles of suspected criminals before any crimes have actually been committed.

The Hesse state government, on the other hand, argues that the program does no more than coordinate data that it has already gathered from other sources — such as surveillance cameras and online public records — and is vital to preventing serious crimes.

'Hessendata' — piecing the puzzle together

What exactly the program can and can't do, and what it can legally be used for, was the subject of Tuesday's hearing, and yet remains unclear — mainly because little is publicly known about the software.

Simon Egbert, sociologist and predictive policing researcher at Bielefeld University, thinks that is the key problem, especially as Hessendata is being searched 14,000 times per year by the police. "The critical public has problems even forming an opinion about what is actually happening," he told DW.

One Hesse government official explained to the court how the tool made normal police work more effective: After arresting a suspect in an ATM robbery, police were able to use Hessendata to analyze his vehicle's navigation device and establish that it had been nearby for other ATM robberies. As reported by the German legal news outlet Legal Tribune Online, this showed that using the software was "very close to traditional police work."

But the software can apparently be much more invasive. The German research and advocacy organization AlgorithmWatch says that Hessendata coordinates information from police databases with phone records and social media accounts to investigate potential criminals and terrorists. The police in Hesse also want to use it to profile child abusers and traffickers.

Concerns about the software, which is now used by many European police forces, have been raised before. Named after the fictional city where Batman fights crime, the Gotham program grew out of the company Palantir's collaboration with US intelligence agencies. According to GFF, its abilities amount to "preventive policing" — that is, using internet data to predict crimes and the identities of criminals.

There are also fears that the program can use AI techniques to racially profile potential offenders. Complaints about racial profiling — and far-right sympathies among officers — have plagued the German police, especially in Hesse.

What comes first? Suspicion or investigation?

Hesse's conservative Interior Minister Peter Beuth insisted on Tuesday that Hessendata does not automatically sift through social media profiles or the internet, and does not use ArtificiaI Intelligence technology, arguing it was simply a platform for integrating already-available data. "Only when we bring all the puzzle pieces of a threat together does the threat become identifiable," he told the judges.

Markus Thiel, a law professor at the German Police University, who represented the Hamburg government at Tuesday's hearing, said that the law is already very clear about what the police can and can't do. "For me, it is very important that the standards we have, both in Hesse law and Hamburg law, formulate clear preconditions," he told DW. "And they say this software is only to be used to prevent serious crimes, and only to avert serious threats."

As it stands, Thiel argued, "the rules do not allow the police to use AI systems to continually monitor citizens in order to create personality profiles at some point in the future," he said. "It's nothing like 'Minority Report,' where you want to predict crimes. The law requires the police to already have information that there is a threat."

Thiel said that Hessendata was essentially a "platform that offers you an overview of the data that you already have. You can for example identify groups of offenders, where before you only had individual facts," he said. "For example, with a ring of child pornography users and producers, it was often very difficult to establish who might be involved. This software can be used for that."

The problem, according to Egbert, is that while the police have to provide a reason to invade privacy, Hessendata by its very nature "works exactly the other way round." A lot of the data that the police have, some of which is indeed gathered on social media, was gathered for totally different investigations. "In other words, when you do a search, you can only really tell afterward whether the search was justified or not," he said.

Civil rights campaigners argue that the key legal principle — that an investigation must be tied to a specific purpose — cannot be guaranteed if Hessendata has access to masses of data that have nothing to do with specific suspects.  

"In my opinion," said Egbert, "it needs to be properly discussed whether that is allowed or not."

Another thing that troubles Egbert is how the Hesse government went about changing its policing law to suit the software. "I do think it's quite questionable that a government decides it wants to use certain software and then just changes policing laws – of course with the required parliamentary majority," he said. "And now four years later it's in Karlsruhe, where the first more or less independent people decide whether that is legal or not."

Complicating an already complex issue is that the Hesse state parliament has also commissioned an investigative committee to establish whether or not the government's procurement procedure was lawful. "That's really just a stand-in issue," said Egbert. "I think that is problematic in itself, that the opposition apparently had no other way of having an influence on the procedure."

The Constitutional Court is not expected to make a decision for several more months – in the meantime, the police in Hesse (and perhaps Hamburg) will continue to use the software.

Edited by: Rina Goldenberg

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