Egypt’s rising authoritarianism has been met with a collective shrug in Washington, which sends Cairo $1.3 billion in military aid each year.

One notable exception is Senator Patrick Leahy, who is raising alarm about human rights abuses Egyptian security forces have committed as they battle militants in the Sinai Peninsula. He recently asked Secretary of State John Kerry in a letter whether Egypt had run afoul of a federal law he sponsored that bars military units that have committed human rights abuses with impunity from receiving American aid.

“According to information I have received, the number of militants has steadily increased, due, at least in part, to ineffective and indiscriminate operations by the Egyptian military and the lack of licit economic opportunities for inhabitants of the Sinai,” Mr. Leahy wrote in the July 20 letter.

Mr. Leahy, a Democrat from Vermont, is asking a rhetorical question. It is abundantly clear to the senator and Egypt experts in the American government that Egypt’s security forces have committed abuses with impunity in recent years. In May, the State Department told Congress in a report that security forces have “committed arbitrary or otherwise unlawful killings during the dispersal of demonstrators, of persons in custody and during military operations in the northern Sinai Peninsula.”

Mr. Leahy’s point is that continuing to enable a despotic government by shipping over American Apache helicopters, missiles and ammunition is not only unwise but almost certainly unlawful. Mr. Leahy points out in his letter that the Egyptian government has prevented American government officials, journalists and human rights organizations from traveling to Sinai to investigate because of safety concerns. The real reason is likely that it wants to keep the evidence of its scorched-earth approach to fighting militants hidden.

That will become even easier for Egypt now that President Abdel Fattah el-Sisi of Egypt granted his government sweeping powers to continue cracking down on the Muslim Brotherhood, a political movement, and other opponents under the guise of fighting terrorism.

The new counterterrorism law, which was formally adopted on Sunday, codifies the harsh and counterproductive approach the government has taken toward the political opposition and establishes new tools to stifle dissent. It will also make getting credible news about Egypt even harder. Publishing information that is at odds with the government’s account of military activities can now be punished with a fine of at least $25,000.

The Leahy law compels the State Department to ensure that military assistance and aid is withheld from foreign troops that have committed abuses without being held to account. Over the years, it has been applied rigorously in some parts of the world and largely ignored in others.

Mr. Leahy’s letter, by calling attention to the fact that the law is being flouted in Egypt, should compel the Obama administration to rethink its feckless Egypt policy. It may also prompt other lawmakers to consider whether their continued largely unconditional support of the Egyptian government is backfiring.

While Egypt undoubtedly faces a genuine terrorist threat, its current approach may well be producing more militants than the government is able to execute or lock up. The implications of that should be of grave concern to the American government.

— The New York Times, Aug. 19