The Congressional Budget Office has released a new estimate of the cost of the PROTECT IP Act, the controversial legislation to force private ISPs, search engines, and other parties to censor websites accused of facilitating copyright infringement. Based on personnel estimates supplied by the Obama administration, the CBO estimates that the enforcement activities of PROTECT IP will cost taxpayers about $10 million per year.

The bulk of the money would be spent on hiring staff. The Justice Department would need additional agents to "commence legal actions against individuals who operate or register an Internet site dedicated to activities infringing on copyrights of others," the CBO says. "DOJ anticipates that it would need to hire 22 special agents and 26 support staff to execute its new investigative responsibilities under the bill."

The price tag for bringing on those new workers? $47 million over five years, or just under $10 million per year. Of course, this is just a rough estimate. The actual costs will be controlled by future Congressional appropriations and the enforcement priorities of the administration.

An extra $10 million in spending is a drop in the bucket in a federal budget that now exceeds $3 trillion. But the estimate comes with two important caveats. First, the personnel requirements were estimated by the Obama administration, which may have an incentive to downplay the bill's costs in order to speed its passage. So it's possible that the government would devote significantly more resources to enforcement once the legislation was enacted.

The bigger concern is that the estimate doesn't include potential costs to the private sector. The Unfunded Mandates Reform Act requires the CBO to estimate whether proposed legislation will cost the private sector more than $142 million. The CBO says it can't do that in this case because of "uncertainty about how often and against whom the Department of Justice or copyright holders would use the authority" provided by the legislation.

We've never had the kind of large-scale Internet censorship infrastructure mandated by the PROTECT IP Act, so it's hard to predict how much it would cost private ISPs, search engines, and credit card networks to comply. But maintaining, updating, and enforcing blacklists could be expensive, and these costs would be multiplied across hundreds, if not thousands, of private firms.