In general, candidates who are on the end of a rescinded offer do not have much in terms of legal recourse. Although it varies from state to state, unless otherwise specified, employment is “at-will”, meaning either the employer or the employee can terminate the employment relationship at any time and for any reason. Consequently, candidates have a difficult time enforcing a job offer or recovering damages for a rescinded offer when there is no duty on the part of the employer to keep the individual employed.

That said, there are some circumstances in which a candidate may have legal recourse if an employer rescinds a job offer. The candidate may be able to pursue a claim against the employer under one of the following theories: 1) Promissory estoppel, 2) Fraudulent misrepresentation, 3) Breach of contract, and 4) Discrimination.

career.mst.edu/…/job-offers-and-rejections/

Promissory estoppel cases are generally a case of the juice not being worth the squeeze, but based on the information in the OP (i.e. hefty demonstrable sunk costs) this particular circumstance might be an exception.