Many libertarians (of the type I call Reasonite libertarians ) claim borders are arbitrary (see this clichéd outburst where one describes the United States border as “a damned line in the sand”), therefore protecting borders is unjust, an infringement on the rights of non-citizens to live and work wherever they want. As Chris Roach observes , “Wouldn't many people who violate property rights--including these stalwart immigrants who trespass upon ranches in South Texas while in transit--also merely be "crossing a damned line in the sand"?" Private property aside, if national borders are arbitrary, similar borders within nations must also be arbitrary: the ‘borders’ of national and local parks, for example. If it’s wrong to prevent illegal aliens from entering the nation to live and work, it’s similarly wrong to draw a line in the sand to prevent illegal aliens, once here, from entering, living, even working, in parks. One might argue since parks exist for the benef...