It’s not just newspapers that are losing paid readership.

Flagship law reviews have seen paid circulation decline significantly during the past three decades, with some facing particularly steep drop-offs lately, according to a study by a professor at the George Mason University School of Law.

Ross E. Davies based his findings on information collected by the U.S. Postal Service to track the paid circulation of 21 law reviews from some of the most prestigious U.S. law schools between 1979 and 2009. The publications submit the information to qualify for bulk-rate postage rates.

The reported paid circulation for the Harvard Law Review, Davies found, was 8,760 in 1979 but a mere 2,029 in 2009 — a decline of nearly 77%. Paid circulation for The Yale Law Journal dropped by more than 57% — from 4,051 in 1980 to 1,725 in 2009.

“I started looking at this last year just out of curiosity, so I gathered the data and I was struck by the trend,” Davies said.

Davies offered several theories for the decline. For one thing, he said, readers no longer need a paid subscription to view a law review’s content. The emergence of legal information services like Westlaw and Lexis has allowed academics and practicing attorneys to read review articles without direct subscriptions. Law review articles are available for free elsewhere on the Internet, too.

Additionally, the target audience for general-interest law reviews has declined. “Over the past couple of decades, my impression is that law reviews have come to view their primary market as academics and not practicing attorneys,” Davies said. “There’s been a decline in products being produced for the mass market.”

Rival law schools present another market for law reviews, but they don’t tend to need multiple hard copies because these publications can be shared in a reading room or online.

Davies didn’t track paid circulation of more specialized reviews, but theorized that they may attract a greater percentage subscribers who are practicing attorneys.

Shrinking paid circulation doesn’t necessarily mean that fewer people are reading law review articles. It’s possible, Davies said, that more people are reading reviews than before because so many are available online.

The increasingly academic focus on flagship journals may mean that it takes longer for ideas they present to find their way into real-world legal practice, he said.

Declining paid circulation probably isn’t hurting reviews much financially; they are relatively cheap to produce because contributors and editors are mostly volunteers. Printing costs tend to be low because the publications lack photos and hard bindings, Davies said.

Still, there’s cause for concern, Davies said. “The worry is on the influence end. The question is now, ‘How useful are we?’ “

Karen Sloan can be contacted at ksloan@alm.com.