Five categories of foreign workers can obtain U.S. immigrant visas (that is, lawful permanent residence or a green card). Within the second "preference" category is a subcategory known as EB-2(B), meant for foreign nationals of exceptional ability in the sciences, arts, or business. The person must either have a job offer from a U.S. employer or qualify for what's called a national interest waiver (NIV).
Typical cases of who qualifies for an EB-2(B) visa might include economists, lawyers, doctors, veterinarians, physicists, market research analysts, geographers, mental health workers, and marriage and family therapists.
The exceptional ability subcategory is easily confused with the employment first preference priority worker subcategory for persons of extraordinary ability, but the requirements are slightly less narrow. (However, people with jobs in education and athletics are left out of this second preference subcategory.)
The main benefit of the EB-2(B) subcategory is that the foreign worker need not have received international acclaim in the field of specialty. Proven sustained national acclaim will meet the required standard. The worker must, however, still be considered significantly more accomplished than the average person in the same profession.
If the EB-2 worker's presence can be shown to hold benefit for the U.S. in the future, it may be possible to submit an application in this category without first getting a job offer or labor certification, through what's called a national interest waiver. (Labor certification is a long and complex process described under Procedures to Sponsor a Worker for a Green Card.)
In order to demonstrably "benefit" the U.S., applicants will have to show that their work there will favorably impact the U.S.' economic, employment, educational, housing, environmental, or cultural situation, or some other important aspect of U.S. life.
The impact must be national in scope: A public health researcher at a federal agency or a university might pass, for example, while the same person coming to provide direct services at a community clinic would probably not.
Applicants will also have to show that the field of work has "substantial intrinsic merit"—in other words, that it is worthy in and of itself. In addition, applicants will need to demonstrate that the work will prospectively benefit the U.S. national interest to a substantially greater degree than that of a similarly qualified, available U.S. worker would. (Unfortunately, USCIS often reinterprets this requirement to mean showing that being forced to go through the labor certification process would actually have an adverse impact on the U.S. national interest. A local labor shortage is not considered to be an adverse impact.)
Because the combination of the above criteria is difficult to satisfy, obtaining a national interest waiver is harder than applicants usually expect, and a lawyer's help is definitely in order.