Senators Diane Feinstein and Dick Durbin are attempting to narrow the definition of a journalist in the federal shield law under consideration by the Senate Judiciary Committee this morning. Their amendment would limit protection from testifying to professional journalists working for “a newspaper, book, magazine, or other periodical.” Not included: student journalists, amateur bloggers, or even freelancers working without a contract.

Markos Moulitsas had the news last night. I’ve been on the phone this morning with people who have worked on the bill, and the consensus is that Feinstein and Durbin are introducing the amendment out of national security concerns: If the shield law is too broad, they reason, it could afford protection to criminals and terrorists who claim the mantle of journalism. Neither senator’s office has returned my calls, and it’s not clear if the amendment will be adopted at today’s committee meeting.

The version of the shield law already passed by the House (H. 985) defines a journalist in monetary terms, covering only those who gather and disseminate information “for a substantial portion of the person’s livelihood or for substantial financial gain.” The Senate has waffled between a similarly professional definition and one that would cover amateurs. The White House, which had dragged its feet on the shield law over national-security concerns, is said to support the broader definition.

A number of news-industry groups, including the Newspaper Association of America, are also supporting coverage for amateurs. Kevin Goldberg, general counsel for the American Society of News Editors, told me today: “There are already exemptions for national security in the bill. If the concern is that the guy holding the video camera for an Osama bin Laden tape is not going to have to testify, that’s a little far-fetched.”

Feinstein and Durbin have leverage here: “If those two really stick to this hard and say we won’t pass a bill without this langugage, they could make a lot of trouble because they are the swing Democrats on this bill,” Goldberg said. However, Senators Jon Kyl and Jeff Sessions, both Republicans, are the only members of the Senate Judiciary Committee who are known to oppose the bill in its entirety, so the support of Feinstein and Durbin may not be necessary.

Today’s committee meeting is underway, so we’ll see. In the meantime, you can read the proposed amendment below and try to parse who might or might not be covered. Goldberg said he’s concerned the language, in addition to excluding amateurs, could omit freelance reporters and photographers doing work without a contract. In addition, he said, “depending on how you define periodical, could exclude web-based publications like Slate and Salon.”