This decision means that CSS encryption can no longer be defined as "an efficient technical action" under copyright law as programmes to decipher it are freely available on the internet.
The court's decision relates to a case where two young men were accused of creating and distributing a programme to de-encrypt CSS protection.
The Helsinki District court dismissed criminal charges against the two on Friday. Its decision was the first of its kind since stricter copyright laws were adopted in Finland in 2005.
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