Sen. John Kerry, a senior Democrat, and technology giant Microsoft Corp. on Wednesday backed the Obama administration's call for broad privacy legislation at a Senate hearing that also exposed hurdles to passing such a law.

"Modern technology allows private entities to observe the activity of Americans on a scale that is unimaginable, and there is no general law" governing the collection and use of that data, Sen. Kerry told the Senate Commerce Committee.

The Massachusetts lawmaker said he was working with others and soon planned to introduce a "privacy bill of rights."

The Commerce Department called at Wednesday's hearing for a privacy law that includes enforceable protections for consumers' personal information and a stronger role for the Federal Trade Commission.

Unlike the European Union, the U.S. doesn't have a federal law establishing a general right to privacy. U.S. laws protect only certain types of information, such as some data about health care or personal finances.