In a closely-watched case, Max Schrems and 25,000 other users are suing the social media giant for various rights violations, ranging from the "illegal" tracking of their data under EU law to Facebook's involvement in the PRISM surveillance programme of the US National Security Agency.
Each of the plaintiffs is claiming a symbolic sum of 500 euros (USD 540) in damages.
However, Facebook's legal team argue that the case is not admissible in an Austrian civil court because "there is no legal basis for a US-style class action".
The judge is expected to issue a written ruling at the earliest in three weeks.
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The case has been brought against Facebook's European headquarters in Dublin, which registers all accounts outside the United States and Canada -- making up some 80 percent of Facebook's 1.35 billion users.
Schrems was able to file his action against the Irish subsidiary at a civil court in Vienna because under EU law, all member states have to enforce court rulings from any other member state.
In response, Wolfram Proksch accused Facebook of not wanting "to be sued anywhere".
"The point is that under EU law, the consumer doesn't have to travel all the way to California to sue giant tech companies, but can do this in his or her home country," he said.
After the hearing, Schrems told reporters he felt confident the case would go to trial.
"From the very start, we have only focused on things which are unambiguous, verifiable, and don't require an expert," he said.
He added that Facebook's legal strategy so far had consisted of "completely avoiding the topic at stake, namely data protection".
"But the key point is whether my data will be safe online," he said.