According to a story at Android Police, a number of developers of Android apps which have the capability to block ads in Web browsers have received notifications from Google that their apps have been kicked out of the Google Play store and are no longer available for download.

The notifications from Google clearly note that the reason the apps are being pulled is because they violate the Google Play Store's developer agreement:

REASON FOR REMOVAL: Violation of section 4.4 of the Developer Distribution Agreement. After a regular review we have determined that your app interferes with or accesses another service or product in an unauthorized manner. This violates the provision of your agreement with Google referred to above.

A search for "adblock" on the play store this morning returned no relevant results, and directly accessing a URL for an ad-blocking package shows the package's page and a notice that the app is "no longer available."

The open nature of the Android platform means that for skilled users, the removal of the apps from the Google Play Store is more a nuisance than an actual deterrent. For example, AdAway, one of the popular applications, can still be obtained by following the instructions on the developer's page and switching to F-Droid, an open alternative to the Google Play store.

Android Police observes, and we agree, that ad blockers do indeed constitute a pretty clear violation of the Play Store developer agreement's terms of service—though, in typical legal fashion, the language is broad. Section 4.4, "Prohibited Actions," reads as follows:

4.4 Prohibited Actions. You agree that you will not engage in any activity with the Market, including the development or distribution of Products, that interferes with, disrupts, damages, or accesses in an unauthorized manner the devices, servers, networks, or other properties or services of any third party including, but not limited to, Android users, Google or any mobile network operator. You may not use customer information obtained from the Market to sell or distribute Products outside of the Market.

That clause could arguably be used to remove almost any app for almost any reason, but Google's decision is certainly a sensible move. Of course, determined folks will still find a way around it, as they always do.