of the PCA, civilian leaders, working in conjunction with their military counterparts, should consider certain factors.
The PCA applies to—

• active duty personnel in the Army, Air Force,7 Navy and Marines;8

• armed forces reservists on active duty, active duty for training, or inactive duty for training;

• National Guard personnel in federal service (Title 10 status); and

• civilian employees of the Department of Defense (DoD) when under direct command and control of a military officer.9

The PCA does not apply to—

• members of a military service when off duty and acting in a private capacity. (Members are not acting in a private capacity when assistance to law enforcement officials is rendered under the direction or control of DoD authorities;10)

• members of the National Guard when not in federal service;

• members of a reserve component when not on active duty, active duty for training, or inactive duty for training; and

• members of the Coast Guard during peacetime.11 (Hence, the requirement for the U.S. Navy in the performance of its counterdrug missions to have Coast Guard law enforcement detachments board suspect vessels and effect arrests.12)

If it is determined that the PCA applies to the category of military unit providing support to a law enforcement agency, the next issue is to understand the limitations on the type and circumstance of the mission. In other words, what military operations are covered or proscribed by the PCA?

What PCA and DoD Implementation Regulations Proscribe

PCA and DoD implemention regulations proscribe direct law enforcement assistance, including—

• interdiction of a vehicle, vessel, aircraft, or other similar activity;

• a search or seizure;

• an arrest, apprehension, stop and frisk, or similar activity; and

• use of military personnel for surveillance or pursuit of individuals, or as undercover agents, informants, investigators, or interrogators.13

There are three separate tests that courts apply to determine whether the use of military personnel has violated the PCA. The first test is whether the action of the military personnel is “active” or “passive.”14 An example of active participation is a military member assuming an undercover role or effecting an arrest. Passive participation is exemplified by the military’s conduct of area surveillance or the providing of transportation or training. The more active the military members’ participation becomes, the more likely such participation violates the PCA. The second test is whether use of the armed forces pervades the activities of civilian law enforcement officials. 15 In other words, are the military members expected to perform traditional police investigative or enforcement roles? If so, then the PCA may preclude such activity. The final analysis is whether military personnel subject citizens to the exercise of military power that is regulatory, proscriptive, or compulsory (a power compulsory in nature is one that exerts some coercive force).16 For instance, if the use of the military would subject civilians to military judicial and administrative sanctions, such use probably violates the PCA.

When the PCA Does Not Apply

The PCA does not apply when actions further a military or foreign affairs function of the United States. This sometimes is known as the “Military Purpose Doctrine.” The primary purpose must be to further the military interest. The civilians may receive an incidental benefit. Such military purposes include the following:
• Investigations and other actions related to enforcement of the Uniform Code of Military Justice (UCMJ).17