Previously, we wrote about the DOJ's attempts to justify invasive surveillance with the All Writs Act, a federal law that empowers federal courts to issue any "necessary or appropriate" court order. The government was trying to convince Federal Magistrate Judge Orenstein that he could authorize the government to track someone's location using their cell phone—without a search warrant and despite the lack of any statute allowing such surveillance.

It now looks like Orenstein, who just issued a decision reaffirming his denial of the government's request, saw the DOJ's argument for the snake oil it was:

The government thus asks me to read into the All Writs Act an empowerment of the judiciary to grant the executive branch authority to use investigative techniques either explicitly denied it by the legislative branch, or at a minimum omitted from a far-reaching and detailed statutory scheme that has received the legislature's intensive and repeated consideration. Such a broad reading of the statute invites an exercise of judicial activism that is breathtaking in its scope and fundamentally inconsistent with my understanding of the extent of my authority.

(Read more after the jump.)

We wholeheartedly agree. The All Writs Act should not become an all-purpose tool for surveillance without probable cause, whenever the DOJ feels that compliance with surveillance statutes is inconvenient, or whenever it wants new surveillance powers that Congress hasn?t authorized. Unfortunately, though, it seems the government has already had some success at convincing judges to treat the All Writs Act as the Swiss Army knife of surveillance, authorizing such novel spying ideas as the credit card wiretap, or ?hotwatch? order.

In briefing this case, the DOJ revealed that it has often gotten court authorization under the All Writs Act for these orders, which ?direct a credit card issuer to disclose to law enforcement each subsequent credit card transaction effected by a subject of investigation immediately after the issuer records that transaction.? This is shocking stuff?Congress has never authorized such surveillance, and no published court decision has ever considered its legality. And it leads to the obvious but very discomforting question: what other new surveillance powers has the government been able to justify using the All Writs Act, and for how long? Until a judge denies a government request and publishes the decision, like the judges in the current cell phone tracking cases, we?ll never know.

Although ?hotwatch? orders were not at issue in the cell phone tracking case, Judge Orenstein noted that the ?government cites no decision approving the use of the All Writs Act for such purposes,? and pointedly refused to endorse the practice. Hopefully, the next court asked to sign a ?hotwatch? order?or a cell phone tracking order, or whatever other new surveillance order the DOJ dreams up?will follow Judge Orenstein?s lead and require a search warrant based on probable cause. That way, the All Writs Act won?t become the All Surveillance Act.