TL;DR

At-will employment is a US legal doctrine, applying in all states except Montana, that allows either party to end an employment relationship at any time, for any non-prohibited reason, without advance notice or severance. For staffing agencies, this means the workers they place are typically at-will unless a written contract says otherwise, and clients can end assignments without cause. However, at-will does not override discrimination law, WARN Act obligations, or contractual rights created by offer letters and handbooks.

What At-Will Employment Means for Staffing Agencies

When a staffing agency places a W-2 worker with a client, that worker is typically employed at-will by the agency -- not by the client. The agency, as employer of record, can end the employment relationship at any time for any lawful reason. The client can likewise pull the worker from the assignment without explanation. But "at-will" does not mean consequence-free. Because the agency retains employer status, any protected-class animus the client may have exercised in requesting an assignment end can still expose the agency to an EEOC charge. Courts have consistently held that staffing agencies cannot simply pass discriminatory client decisions through to workers and claim immunity.

The practical implication is that when a client calls asking an agency to "end" a placement, the agency should document the reason. If a client says a worker "isn't a cultural fit" after that worker filed a workplace safety complaint, the agency faces potential retaliation exposure even though the client made the call. Agencies that operate in multiple states must also track at-will modifications: offer letters that use language like "you will have a job as long as you perform well" or handbooks that describe progressive discipline procedures before termination have been found by courts to create implied contracts that override at-will status.

The Three Exceptions to At-Will Employment

Three major legal doctrines limit what employers can do under the at-will banner, and all three can surface in staffing contexts. The first is the public policy exception, which prohibits terminating an employee for reasons that violate a clearly established public policy -- such as firing a worker for serving on jury duty, filing a workers' compensation claim, or reporting a workplace safety violation to OSHA. Most states recognize this exception, and it applies whether the employer is the staffing agency, the client, or both under a joint employment analysis.

The second is the implied contract exception. Handbook language that says "employees will not be terminated except for cause" or "we use a three-step disciplinary process before termination" can be read as a promise. Courts in roughly 40 states recognize implied contracts created by employer communications, meaning agencies need to review every document workers receive -- offer letters, handbooks, orientation materials -- for language that might imply security beyond at-will. The safest practice is an explicit, signed at-will acknowledgment.

The third exception, the implied covenant of good faith and fair dealing, is recognized in fewer than 15 states, with California among the most notable. Under this doctrine, even an at-will employer cannot terminate in bad faith -- for example, to deprive an employee of an earned bonus or commission.

At-Will Employment in the US vs UK

The US at-will doctrine has no equivalent in the UK. Under the Employment Rights Act 1996, UK workers gain the right not to be unfairly dismissed after two years of continuous employment. Before that two-year mark, dismissal is generally lawful without stated cause -- but statutory notice periods apply from day one. An employee with less than two years' service is still entitled to one week's notice per year of employment, minimum one week total.

UK employers must also follow ACAS Code of Practice on Disciplinary and Grievance Procedures when terminating for performance or conduct reasons. Staffing agencies that operate in both US and UK markets therefore design their assignment-end processes very differently depending on jurisdiction. A client pulling a UK placement without notice and documented reason faces a much higher legal risk than the same action in a US at-will state.

Reducing At-Will Risk in Temp Staffing

A healthcare staffing agency placing per diem nurses learned this lesson when a client hospital asked the agency to remove a nurse from the schedule without explanation the week after that nurse complained about patient safety conditions. The agency complied without documenting the client's rationale. The nurse filed a retaliation charge against both the hospital and the agency. The agency ultimately paid a portion of the settlement because it had no documented, non-retaliatory business reason for ending the placement.

The practical steps that reduce at-will risk are operational rather than legal: document the business reason for every assignment end, even brief ones; include explicit at-will language in all offer letters and have workers acknowledge it in writing; review client service agreements to ensure clients are required to provide a non-discriminatory reason when pulling a worker; and train recruiters to recognize when a client's stated reason sounds like a pretext for discrimination.