COL. DENISE LIND, the U.S. Army judge who heard the charges against Pfc. Bradley Manning for the leak of tens of thousands of secret documents to WikiLeaks, offered a ruling that will echo long after the sentencing of the 25-year-old private. She acquitted Pfc. Manning of a charge that leaking the secrets was “aiding the enemy,” or the highest form of treason, while convicting him of lesser charges that may still bring a long prison term.

Col. Lind did not explain her decision, which goes to the heart of a debate that has been raging with multiple prosecutions underway of leakers and disclosures by Pfc. Manning and Edward Snowden of classified materials. In effect, Col. Lind declared that leaking is not necessarily tantamount to treason. Certainly, traitors have betrayed the country before and will do so again, but it is an important distinction that not every leak of a government secret rises to the level of treason, and leaks can often play a vital role in shaping public opinion.

As a newspaper, The Post thrives on revelatory journalism and often benefits from leaks, sometimes inspired by dissent and other times by spin. The Web site WikiLeaks, which published the raw material provided by Mr. Manning as well as other secrets, differs from journalism in methods if not goals. The Post and many others in print and broadcast journalism sift and check information and take care not to reveal sources and methods or to endanger lives in bringing secrets to light. WikiLeaks and Pfc. Manning showed less care. They spilled classified government data into the open, in some cases endangering individuals who were identified in diplomatic cables. Pfc. Manning had taken an oath to protect secrets, which he broke. No system of secrecy can function if people ignore the rules with impunity; it is reasonable that Pfc. Manning be punished in some way for breaking those rules.

However, the Manning verdict casts light once again on the fact that far too much information is classified. The Public Interest Declassification Board concluded last year that classification practices are “outmoded, unsustainable and keep too much information from the public.” Too many people can slap “top secret” on a document with too little justification for doing so. Steven Aftergood of the Federation of American Scientists, writing in the Harvard Civil Rights-Civil Liberties Law Review, concludes that existing principles for determining what should be secret are far too broad, especially in national security, giving officials “all but unlimited discretion” to classify as they see fit.

When too much is routinely classified, it undermines the credibility of the system, including the protection of vital secrets, and erodes public trust. This administration’s pursuit of leakers has outstripped any previous administration. What’s desperately needed is more restraint — and an overhaul of the classification system to preserve the proper use of secrecy in an open democracy.