As a "once-upon-a-time" union executive officer, I can't offer legal advice; but I can perhaps suggest where to look for help.

It is fairly unusual for most individuals employees to have a formal contract. If the person does have one, then what's written in the contract is what rules.

There are some cases where a company is required to have, and to publish, company policies and in some cases "rules of conduct" for employees. If the company has published any such, they should be generally enforceable, but tend to favor the company rather than the employee. If the company has ignored a requirement, and failed to produce any such required documents and make them available to all affected employees, one can probably make a strong legal case for just about any whim suggestive of maltreatment - but (in my best guess) it will require very excellent legal counsel.

If there isn't a contract between the individual and the company, there may be an employment agreement stating minimal working conditions and method (and sometimes amounts) of payment. Beyond what is stated in that agreement, and published company polies, most people are "employees at will" and the management is pretty much free to do what they want, including discharge without notice and/or changes in working assignments and conditions.

There are some regulations, especially with respect to harrassment and "inhumane working conditions," usually refered to as "anti-discrimination laws," and there are minimum wage laws that include not only the minimum amount paid but also when "overtime pay" may be required.

Federal laws/regulations generally are enforceable only for companies in "interstate commerce" or for those having contracts with the Federal Government.

State laws may supercede harrassment and minimum wage laws for local companies who don't fall under the Federal regs.

The harrassment and minimum wage laws/regulations - both state and federal - generally do not apply to small companies, and "overtime pay" has so many ways that companies can weasel out of paying it that the work hours and overtime pay regulations are really of little effect.

If there is a union at the company, and if the person is a member of the group eligible for union membership, then the US Federal Law requires that the union must enforce their contract for all "eligible members of the contract group" regardless of whether they pay the dues. (If you want enthusiastic enforement it's probably best to be a member of the union.) In some states, all members of the "organized group" must pay dues whether or not they join the union (called a "check off law") and in some states - so-called "union states" - all eligible members are required to actually be union members. The difference is largely a matter of whether everybody (who pays dues) can vote in the union elections and on new contracts (although where actual membership has been a permitted requirement some unions have used membership quotas to limit competition).

I don't know whether it may be usual for "green card" workers to have more detailed individual contracts than is usual for "citizens." For most of us, the first contact necessary/recommended when maltreatment is suspected - and not resolved directly with local management - usually is the US Equal Employment Opportunity Commission (EEOC); but I don't have experience with whether they considers resident aliens to be part of their responsibility. Assistance one gets from them can be quite variable (based on my experience) but one can get lots of forms and regs to read from them. Personal knowledge of specific regulations that you can cite is probably quite important if one expects a satisfactory outcome in any significant dispute.

For any suspected breach of conduct on the part of a company that might fall under EEOC jurisdiction, it should be noted that most offenses must be reported within specific (usually fairly short) times after the "first cause for complaint" so a prompt look at whether they offer anything should be considered important, if only to determine if deadlines must be met.

Individaul states may have state equivalents to the Federal EEOC, but I have no idea whether Massachussetts has such an office. Web and phone books are a place to start looking.

Hiring one's own attorney is generally impractical (my opinion) unless one has a provable complaint of a company action that violates a specific statute that permits "punitive damages."

Age discrimination cases under the Federal statuts, for example, are not permitted to collect anything except "actual losses" so it's usually impossible even to hire an attorney - because you can't get anything out of the case with which to pay one. Sexual and Racial discrimination - the last time I looked - allow "punitive damages" (2x or 3x the actual loss claimed) and are more viable.

Note that these are just "lay observations" and more informed (and more current) advice should be pursued before making any threats to one's current employer.

John