One potential foundation is the tradition of reading the Riot Act. Normally citizens are allowed to move freely and gather. This is suspended during a riot for public safety. Homeless in general and encampments specifically can be seen as also a menace to public health and safety. Observe and record incidents of disruptive behavior, public drug use and pooping, and calls to responders and at certain level issue a warning then take action. These problem cases can cost communities hundreds of thousands. At some point something has to be done.