I think the argument based on FISA is weak, but otherwise it's good stuff.
Here are some bonus links, just for fun. Not relevant because they are more FISA related, and eeven there, more to the point of threshhold for obtaining a FISA warrant.
Senate statment re: warrants and "substantial" v. "significant" purpose ...
http://www.fas.org/irp/congress/2002_cr/hatch-fisa.html
KYL: Until Senator Schumer arrives, I make another point. There has been a worry on the part of some that this expands the Foreign Intelligence Surveillance Act to private American citizens. I make it crystal clear that is not true. ...SCHUMER: Here is the problem. They also must show under present law that the target is an agent of a foreign power, such as Iraq, or a known foreign terrorist group, such as Hamas or al-Qaida. That is the hurdle we are removing. If that requirement had not been in place, there is no question the FBI could have gotten a warrant to do electronic surveillance on Zacarias Moussaoui and, who knows, not certainly but perhaps, 9/11 might not have occurred.
That is the anguish we all face. Right now we know there may be terrorists plotting on American soil. We may have all kinds of reasons to believe [[Page S5902]] they are preparing to commit acts of terrorism. But we cannot do the surveillance we need if we cannot tie them to a foreign power or an international terrorist group. It is a catch-22. We need the surveillance to get the information we need to be able to do the surveillance. It makes no sense. The simple fact is, it should not matter whether we can tie someone to a foreign power. Whether our intelligence is just not good enough or whether the terrorist is acting as a lone wolf or it is a new group of 10 people who have not been affiliated with any known terrorist group, should not affect whether we can do surveillance, should not affect whether they are a danger to the United States, should not affect whether they are preparing to do terrorism. Engaging in international terrorism should be enough for our intelligence experts to start surveillance.
It is important to note if we remove this last requirement now it will immeasurably aid law enforcement without exposing American citizens or those who hold green cards to the slightest additional surveillance. ...
NAYS--4: Byrd, Durbin, Feingold, Harkin
NOT VOTING--6: Biden, Graham (FL), Kennedy, Kerry, Lieberman, Murkowski
Senate debate re: "lone wolf" provision for obtaining a FISA warrant ...
http://www.fas.org/irp/congress/2003_cr/s050803.html
Very interesting discussions; thanks for the ping to this and the easier read in #190 of the Asst AG's letter.