ken_b - 5:39 pm on Sep 2, 2009 (gmt 0)

Here, I found it:

[copyright.gov...]

If the subscriber serves a counter notification complying with statutory requirements, including a statement under penalty of perjury that the material was removed or disabled through mistake or misidentification, then unless the copyright owner files an action seeking a court order against the subscriber, the service provider must put the material back up within 10-14 business days after receiving the counter notification.

I suppose the 10 - 14 days could be too long a time for some time sensitive issues.