The move has been temporarily suspended over fears incoming EU legislation could cause the city a huge patent headache. Munich's pro-Linux, Green Party alderman Jens Muehlhaus has spotted 50 potential patent problems. Until they've been sorted, the migration is on hold.
The planned call for bids on the 'LiMux project' -- due for next week -- has been stopped as Muelhaus feared that in the result of a patent clash, the city could be forced to pay for extra licensing fees or even shut down its IT systems.
According to the Open Source Risk Management Association, Linux may even infringe 283 patents. A recently unearthed memo from HP revealed that "basically Microsoft is going to use the legal system to shut down open-source software".
The city of Munch, however, is standing by its decision to switch and maintains the hold-up is temporary. Before embarking on the migration, Munich carried out a year-long feasibility study with help from Novell-parented SuSE and IBM.
The deal was seen as so significant that the proposed changeover even got Microsoft chief executive Steve Ballmer to cut short his holidays to try to persuade the mayor of Munich in person.
Munich has taken the lead in public sector Windows-to-Linux switches and was followed by Norway's second city, Bergen, last month. Vienna has also been eyeing up a switch but has recently decided to offer a choice of either open source or Windows to half its users from next year, with a review to follow in 2006.