Actually, they point to an independent report that says they are doing a reasonable job stopping click fraud. Does that mean any click fraud that they allow is reasonable too? Here‘s the scoop, right off the Google blog:

As part of the settlement in the click-fraud case Lane’s Gifts v. Google, we agreed with the plaintiffs to have an independent expert examine our detection methods, policies, practices, and procedures and make a determination of whether or not we had implemented reasonable measures to protect all of our advertisers. The result of that is a 47-page report, written by Dr. Alexander Tuzhilin, Professor of Information Systems at NYU. The report was filed with the court in Texarkana, Arkansas, this morning.

The bottom-line conclusion of the report is that Google’s efforts against click fraud are in fact reasonable. At several points in his report, he calls out the quality of our inspection systems and notes their constant improvement. It is an independent report, so not surprisingly there are other aspects of it with which we don’t fully agree. But overall it is a validation of what we have said for some time about our work against invalid clicks.