Someday I'll tell my children about a quaint time early in the new millennium when a lot of people were outraged that a law called the Patriot Act allowed the federal government to investigate an individual's checkout record from the library. Then I'll try to explain what a library card is.

Of course, there are more pressing matters at stake than the last time you borrowed the Bhagavad Gita, as Rand Paul demonstrated with a filibuster-like technique this weekend that blocked renewal of a few provisions of the law, in the name of defending Americans from the bulk collection of their phone metadata. Metadata may sound abstract, but it reveals a picture that is substantially more informative than what a private investigator could put together if he were surveilling you 24 hours a day. Your exact location, your contacts, and how often you communicate with them — together these form a pattern of behavior.

Paul argues that such collection amounts to a violation of the Fourth Amendment's protections against unreasonable searches and seizures, and that it infringes on our reasonable expectation of privacy.

Paul's maneuver generated enthusiasm from his supporters, but a lot of eye-rolling and charges of demagoguery from his detractors. He countered, "The people who argue that the world will end and we will be overrun by jihadists are trying to use fear. Little by little, we've allowed our freedom to slip away."

Paul wasn't alone either. Sen. Ron Wyden, Democrat from Oregon, celebrated his move: "Tonight the collection of phone records of millions of innocent Americans will end... The demise of this dragnet surveillance is a victory for the principle that Americans do not need to sacrifice liberty to have security."

Now, not everything about this event was a success. It requires a Democrat's faith in bureaucratic competence and obedience to believe that at the stroke of midnight, officials at the National Security Agency dutifully flipped a handy switch that somehow ended the collection of metadata — at least for the few days it will take Congress to reauthorize it. Paul also used his time, perhaps unwisely, to generate anger at the USA Freedom Act, a replacement law that arguably restricts or makes more transparent the very practices that Paul finds so injurious to liberty. And he probably went a rhetorical step too far when he said his opponents are wishing for an attack on the American homeland so they can blame him.

But Paul did some interesting and daring things by forcing the sunset of a few Patriot Act provisions. He potentially burned some bridges with his colleague Mitch McConnell, whom he has been developing as an ally almost from the day he was elected to the Senate. Paul also reversed his recent trend of moderating his libertarian critique of the post-9/11 security state and foreign policy, and by doing so started a big debate within a party that has unfortunately reverted to hawkishness after the rise of ISIS.

That last bit is important. As a dozen or more people seek the Republican nomination, some with as much Tea Party cred as Rand Paul, each candidate needs a rationale. Paul's recent attempts at moderation effaced his distinctive appeal. It gave his most die-hard supporters jitters, and made him less interesting as a potential reformer of his party and as a subject for the media. For that reason alone, Paul's move against the Patriot Act was smart politics.

Paul's gambit can also be justified for attracting more eyeballs to the debate about privacy issues and digital security. Because Paul is a figure of interest, and because legislative grandstanding is a guaranteed way to attract the Sauron's Eye that is the media, he made these issues come alive again — all at a time when Americans seem quietly resigned to federal (and private) authorities reading their lives like an open book. As Charles Cooke helpfully points out, the passive collection of metadata creates new and unsettling occasions for abuse.

We live, alas, in a world of rogues and of hackers and of blood-sucking incompetents — and this means that each and every time that we compile a database there is a substantial risk that it will be abused or stolen or left somewhere on a train. [National Review]

Even if you believe Paul's effort is tainted by self-interest, or a slight confusion on the details, he performed a service by reminding us of the toll taken on our liberty by the war on terror. He also gives me hope that someday we'll return to quaint debates about the sanctity of our library cards.