Two natural rights were highlighted with respect to human migration and immigration in Immigration-Migration Conflicting Rights:
(a) The right to migrate into Space.
(b) The right to secure settled space.
It was also highlighted in the aforementioned article that immigration policies are just and meaningful only if they are based on the desire to secure settled space because the right to secure settled space overrides the right to migrate into Space. This security may be broadly or restrictively defined by policy makers depending on who holds the rein of power. For some, it includes economic, political and social security. For others, such threats are non-existent. Physical security (direct harm to person and property) is usually universally understood. Observe the current stalemate among the political leaders in the United States of America with respect to how to secure its southern border.
The ability to manipulate situations negatively is one of the negative aspect of human intelligence. This human trait often complicates what otherwise may be simple problems. Consider the case of securing the southern border of the United States of America: this is a simple problem if the objective is clear. Is the objective to prevent all illegal entries from this border into the United States and is this objective wholly implementable given the extent of the border? Note that an entry is illegal only because it has not been vetted. It is the vetting that adjudicates the right to migrate into space. So, vetting should never be contentious. Millions of people go to various embassies all around the world to be vetted when they seek to enter settled spaces. In fact these individuals are charged exorbitant non-refundable fees inorder to be vetted and at the end of the vetting many are denied entry. However, all vettings should be humanitarian and benevolent.
Walls are time-tested means of controlling access into space. They are manisfested in various forms. There are even invisible walls. A wall is moral or immoral depending on its function (see Good Walls Bad Walls). The immigration policies of any country should be consistently fair across the board. At the heart of this fairness is the granting of the conditional right to migrate into space given that the right to secure space has been sincerely adjudicated.