In which scenario would the use of federal troops be permitted for law enforcement under certain conditions?

The use of federal troops for law enforcement purposes is primarily permitted under the scenario of insurrection or rebellion. This legal framework is primarily governed by the Insurrection Act, which allows the federal government to deploy military forces to maintain order and suppress insurrection when local authorities are unable or unwilling to do so. The idea is to restore peace and uphold the law during civil disturbances that threaten the stability of the nation.

In contrast, while federal troops may be deployed for humanitarian assistance, natural disaster response, or search and rescue operations, these scenarios typically involve support roles rather than law enforcement. For instance, in disaster situations, troops might provide logistical support or help with recovery efforts, but they are not used to enforce laws or maintain public order. Therefore, the specific conditions surrounding insurrection or rebellion distinguish it as the appropriate scenario for the deployment of federal troops under law enforcement duties.