CISPA would allow Internet Service Providers and other Web-themed companies to share information about their users with the government and one another under the guise of "cyber-security" – with increased protection against any privacy lawsuits that their users might bring as a result.
This means a company like Facebook, Twitter, Google, or any other technology or telecoms company, including your cell service provider, would be legally able to hand over vast amounts of data to the U.S. government and its law enforcement — for whatever purpose it deems necessary — and face no legal reprisals.