The general purpose of the FLSA is to prohibit employers from not paying employees, and to enforce minimum wage standards (there are different wage standards for hourly and professional workers but you still have to pay people if they’re working for you).
The two exceptions to this principle are “internships” and “volunteering.” (The latter exception doesn’t apply to for-profit enterprises). In theory internships are supposed to be limited to educational training that doesn’t displace paid workers. This rule can be and is regularly abused, but the most flagrant abuse of the statute is now taking place in the public sector, through the semantic torture of the noun and verb “volunteer.”
Here’s the relevant definition in the Code of Federal Regulations:
§ 553.101 “Volunteer” defined.Conducting a hiring process that is precisely identical in every detail for two positions that involve doing precisely the same job for the same time period under the same terms of employment, except you pay one of your hires as a GS-11 or GS-12 and pay the other nothing, appears to me to empty the concept of “volunteer” of all meaning.
(a) An individual who performs hours of service for a public agency for civic, charitable, or humanitarian reasons, without promise, expectation or receipt of compensation for services rendered, is considered to be a volunteer during such hours. Individuals performing hours of service for such a public agency will be considered volunteers for the time so spent and not subject to sections 6, 7, and 11 of the FLSA when such hours of service are performed in accord with sections 3(e)(4) (A) and (B) of the FLSA and the guidelines in this subpart.
(b) Congress did not intend to discourage or impede volunteer activities undertaken for civic, charitable, or humanitarian purposes, but expressed its wish to prevent any manipulation or abuse of minimum wage or overtime requirements through coercion or undue pressure upon individuals to “volunteer” their services.
(c) Individuals shall be considered volunteers only where their services are offered freely and without pressure or coercion, direct or implied, from an employer.
(d) An individual shall not be considered a volunteer if the individual is otherwise employed by the same public agency to perform the same type of services as those for which the individual proposes to volunteer.
On a more general level, what's happening in the legal employment market is that it's becoming the norm for a graduate to spend a year or two after graduation working for either literally nothing, or to something close to the economic equivalent, while trying to get his or her "foot in the door" of a real legal job. So what we're producing is something that's coming to more and more resemble the old apprenticeship system of lawyer training, but with a $200,000+ license fee tacked on.
Naturally this is making it increasingly implausible for people who don't come from serious money to actually become real lawyers. In the new gilded age, that might even be the whole point.