The law preventing the military from assuming a law enforcement role is the Posse Comitatus Act of 1878 (PCA). Congress enacted the law after one of the closest presidential elections in history. Rutherford B. Hayes won the 1876 election by only one vote in the Electoral College. After the election it was discovered that President Ulysses S. Grant had dispatched Army troops throughout the South to be used by federal marshals to influence voting at the polls.
Congress and the courts have made many exemptions to the PCA over the years. The law does not apply to the Coast Guard, or to the National Guard so long as it is not under federal command. Also, the military is allowed to provide equipment, technical assistance, information, and training to law enforcement entities. The president can use the armed services to suppress an insurrection when a governor or state legislature requests assistance.
However, the Department of Defense has always maintained that the PCA prevents the military from performing a search, seizure, arrest, or similar police activities. The Pentagon understands that the goals of the armed services and those of law enforcement agencies are very different, as are their methods. Much has changed in America since 1878, but there are still compelling reasons for preventing the military from serving as a substitute for law enforcement.
The training of soldiers is different from that of police and other members of law enforcement. Soldiers are taught to neutralize a threat immediately, with any force necessary. Law enforcement personnel are trained to remedy a volatile situation by initially taking the least aggressive method. They are taught to draw their guns only when absolutely necessary. To require soldiers to serve as a police force during the tense periods that follow natural disasters would result in unnecessary fatalities.
Law enforcement personnel have responsibilities that soldiers never contemplate. Police officers must respect the legal rights of criminals, even in precarious situations. But as was evidenced by the prisoner abuse scandal in Iraqs Abu Gharib prison, soldiers sometimes have difficulties conceiving of the accused as having rights. And law enforcement must be concerned with collecting evidence for purposes of prosecution. Soldiers are not knowledgeable on these issues.
In 1979 the Departments of Defense and Justice reviewed the limitations imposed by the Posse Comitatus Act. In a report they issued the Defense Department reiterated its desire to continue to adhere to the PCA. The report noted that the PCA protected the military from squandering its resources and becoming involved in legal battles which would prevent it from defending the country.
The military should play a role in the recovery efforts that follow a natural disaster. In fact, it frequently has since the San Francisco earthquake of 1906. But requring soldiers to serve as police officers is misguided. It puts our troops, the nations security interests, as well as the legal rights and very lives of citizens at risk.