The owner of the network was able to prove that he was on holiday when the alleged copyright infringements took place but Germany's federal high court of justice said that the network owner had to bear some responsibility for the actions of a third party using their system.
Many people operate small wireless networks in their home so that devices all over the house can connect to the internet. Networks can be password protected or left open for anybody to use.
A musician sued the owner of an internet connection which had been used to download that musician's music without his permission. The song that was downloaded was subsequently offered for sharing on a file-sharing network.
The musician was Moses Pelham, owner of Frankfurt's 3P record label, according to Billboard magazine.
The owner of the network proved that he was on holiday at the time and could not have downloaded the track himself. But the court said that the owner of the network had a responsibility to ensure that their network was not open for anyone to abuse.
"Private users are obligated to check whether their wireless connection is adequately secured to the danger of unauthorized third parties abusing it to commit copyright violation," the court said, according to news agency Associated Press (AP).
The court said that the network owner did not have to pay damages but had to pay the legal fee for the issuing of a warning to him by the copyright holder because he had not secured the network, according to Billboard. It said that this cannot exceed €100.
AP reported that the court did not make network owners actually responsible for the activities of third parties who used it, and said that users did not have to operate a completely secure network but did should at least set a password for it when setting the network up at first.
Recently-passed UK legislation the Digital Economy Act has raised concerns that users in the UK could be responsible for other people's use of their networks to infringe copyright. Academic Professor Lilian Edwards of Sheffield University warned that this could be an outcome of the Act but that it was so vague that is was hard to be sure how courts would interpret it.