Last month, Adblock Plus maker Eyeo GmbH won its sixth legal victory in German courts, with a panel of district court judges deciding that ad-blocking software is legal despite German newsmagazine Der Spiegel's arguments to the contrary. Now, the reasoning of the Hamburg-based panel of judges has been made public.

According to an unofficial English-translated copy (PDF) of the judgment, Spiegel Online argued it was making a "unified offer" to online consumers. Essentially, that offer is: read the news content for free and view some ads. While Internet users have the freedom "not to access this unified offer," neither they nor Adblock Plus have the right to "dismantle" it. Eyeo's behavior thus amounted to unfair competition, and it could even wipe the offer out, Spiegel claimed.

"The Claimant [Spiegel] argues that the Defendant’s [Eyeo's] business model endangers the Claimant’s existence," reads the judgment, which isn't final because it can be appealed by Spiegel. Because users aren't willing to pay for editorial content on the Web, "it is not economically viable for the Claimant to switch to this business model."

Spiegel asked for an accounting of all the blocked views on its website and a fine to be paid—or even for managers Wladimir Palant and Till Faida to be placed in "coercive detention" of up to two years.

Users have a “legitimate interest”

The three-judge panel found for Eyeo on every point, however. The judges took note of the fact that Spiegel could have done something about ad-blockers. For instance, it could have shut ad-blocking users out from the Web content, linked advertising directly to the website's HTML, or used a kind of anti-anti-advertising software that spoofs ad-blockers.

Spiegel said those options "would not be a long-term solution but rather result in a sustained race to stay ahead of the technological curve." Still, the judges said the newspaper's decision not to use them meant it wasn't clear that the Spiegel website was a "unified offer" that had to be taken or left as a whole.

In order to be found liable for interfering with competition, Spiegel would have had to prove that Eyeo was "acting with intent to cause damage" and also interfered with Spiegel's marketing. The fact that Adblock Plus clearly did have some impact on Spiegel's bottom line isn't enough to show "intent to cause damage," in the judge's view. The ad-block software doesn't single out Spiegel, applying evenly to all websites.

"The action brought forward is unfounded," the judges concluded. "The Defendant is not interfering with the Claimant’s opportunities to realize its market potential... Internet users have a legitimate interest in the prevention of undesired advertising, protection from malicious software and control of their data."

The judgment also contains a few data points about the size and scope of Eyeo's business. As of August 2015, Adblock Plus was installed on approximately 9.55 million browsers with German IP addresses. That's about five percent of the computers in Germany used to access the Internet.

About 3,500 websites are on the Adblock Plus "whitelisting" program that allows for "acceptable ads" to be viewed by default. About 90 percent of those sites don't pay, but the largest 10 percent make payments to Adblock Plus for the white-listing.

While Adblock Plus users can easily turn off even those "acceptable ads," about 75 percent accept the default settings and allow the ads. Eyeo determines what is an "acceptable ad." It bars all moving images and many types of still images, allowing mostly for just static text ads.

Eyeo has won six German court cases challenging its ad-blocking business model. It has won them all so far with a few small caveats. The cases are all in various stages of appeal, however.