A rational approach to profiling
I am, by profession, a business process problem solver. A common cause for problems is more work demanded than the enterprise's infrastructure can handle. One useful method to identify a problem's root cause is known as Pareto Analysis. Most know it as the "80-20" rule - that 20% of a total quantity of something is responsible for 80% of an effect. It's an approximation; in real life the ratio depends on the specific cause and the specific effect.
The Pareto effect teaches us that once one identifies the most common identifying attribute or characteristic of a cause, one should inventory and sort the affected population by the most common problem. This is the most economical and fastest way to address the root cause.
In Arizona, the most identifiable attribute of foreign citizen trespassers is ethnicity. They are from Central America, primarily Mexico. Focus on that population first, then work down the Pareto list until the volume of foreign citizen trespassers is acceptable, as perfection is a waste of time.
By the way, it is incorrect to call these trespassers immigrants, legal or illegal. Foreign citizens are permitted to cross our borders for a host of reasons - to study, to vacation, and sadly, to find work that their own country will not create. But they are not immigrants until they apply for citizenship. Until that moment, when they enter our immigration process, and they are within our borders, they are merely visitors. We have no issues with foreign visitors until they break our laws - by crossing our border without the required paperwork for example - at which time their visitation status is determined.
The proper recourse, in Arizona, is issue an undocumented foreign visitor a travel visa of a politically acceptable length, finger print them, and determine what foreign country they shall return to on upon the travel visa's expiration. If they are later found to overstay their visa, follow the law according to current immigration matters.
Statistics regarding foreign citizen trespassers' country of origin will provide the facts the State Department needs to pursue punitive measures and sanctions against offending governments.
It is also time to amend the US Constitution to recent birth citizenship, as it's abuse by foreign trespassers has promoted an underground economy our infrastructure cannot sustain.
Post script. The Pareto Rule should have applied to all airline security measures after 9/11. Only citizens from an ethnic background consistent with the identifying attributes of the jihadists should have been required to undergo additional screening.