In this respect I am currently working on the design of a program whereby reputable and private insurance companies in Central America (some with foreign owners) will offer to guarantee to the US government to pay a quite significant indemnity (minimum 100.000 US dollars) for each worker that covered by a specific temporary worker-program return insurance does not return home, in a timely manner.
Are we talking about an enforcement program that could have some objectionable human rights issues? Absolutely not! Since the premiums for the insurance will be paid by the migrants themselves, and the program contemplates giving them important discounts based on the collective behavior of the group, it is primarily about creating the right incentive structure, and knowing your client.
In this particular case, on both borders, an additional difficulty is that so many have got it fixed in their brains that a migrant worker is by definition a worker who wants to stay, no matter what, and this is absolutely false. The best antidote for any illegal immigration that I can think of is a true temporary program where everyone understands what it is all about, fully accept the underlying premises, and decide to do the best they can to benefit from the valuable window of opportunity that is being offered to them. In short, extremely good temporary migrant worker programs could be developed if people and lawmakers would just dare to reach out.