Although not raising specific legal concerns concerning Tor, there are a few interesting arguments that have been raised. The most significant of them is related to the Council of Europe’s Convention on Cybercrime. Article 32(a) of the Convention regulates trans-border access to stored computer data where ‘publicly available (open source) stored computer data, regardless of where the data is located geographically.’ Unless domestic law states otherwise, law enforcement may access the same data that is generally accessible to the public and subscribe to or register for services available to the public if needed for this purpose. According to some commentators, access to open-source material for criminal investigation purposes has become generally accepted. Tor is a service freely available for the public. This provision should also apply to law enforcement’s activities that involve employing Tor for collecting evidence.
However, there is a minority view arguing that the mere fact that certain information is publicly available does not imply an absence of restrictions to processing such data. Such restrictions may derive from the means and volume of data collected. Bert-Jaap Koops asserts that the current investigative powers that focus on physical space investigations may need to be revised to fit with the particularities of open-source investigations, especially those that offer extensive automated large-scale search capabilities such as entity recognition image-to-text conversion and automated translation. This is based on the assumption that automated open-source investigations may affect the right to privacy and thereby require a legally codified base to inform the citizens about such a possibility. Should such automated means of data processing be used via Tor or be targeting, for example, Tor hidden services, legal regulation of such large-scale search capabilities might need to be considered by the legislature.