Back in 2011, a firm was hit with toll fraud and racked up a $35,000 bill. The firm refused to pay and fought the issue in court. The court found in favor of the firm and ruled that the service provider did not provide adequate security.
This is the first time I recall seeing such a ruling in the press. Enterprises and service providers deal with responsibility for toll fraud all the time, with the many different results (service provider takes responsibility for the first issue, both parties cover portions of the cost, and the enterprise covers the cost).
Here is a link to the article: