TN visas are for Canadian and Mexican nationals engaged in professional employment (part-time or full-time). This category is fairly similar to H-1B except there is no statutory limitation on the period of stay and, importantly, TNs are non-immigrant visas (H-1Bs, by contrast, are “dual intent”). Under the law, professional employment id defined as requiring “at least a baccalaureate degree or appropriate credentials demonstrating status as a professional.”
The TN regulations specify various categories of professionals that are covered. Other categories will not be permitted. These include: accountant, actuary, architect, computer systems analyst, disaster relief claims adjuster, economist, engineer, forester, graphic design, hotel manager, industrial designers, interior designer, land surveyor, landscape architect, lawyer, librarian, management consultant, mathematician, medical/allied professions, veterinarian, range manager, research assistant, scientific technician\technologist, scientist, social worker, sylviculturist, college teacher, technical publications writer, and vocational counselor.
Documentation for Canadians can be presented at the port of entry (no visa is required); no prior petition, labor certification or approval is required for Canadians. Nor is an LCA required. Mexican nationals are no longer required to obtain approved petitions or LCAs, but they are still required to obtain a visa. Every applicant, whether presenting an application at the port of entry, or applying for a visa at the consular post, will need to provide a package from the employer including, among other things, a detailed letter describing the position.