Right-to-Work Law
State laws prohibiting a union security agreement from requiring workers to join a union or pay union dues as a condition of employment, even at a unionized workplace, distinct from whether a state permits unions at all, a right-to-work state can still have plenty of union activity, workers just can't be compelled to financially support it.
Why it matters
Right-to-work status is a state-by-state rule, not a regional or industry norm, so a contractor's labor relations practices in one state can't be assumed to carry over automatically the moment it starts working across a state line.
On a real project
A unionized contractor expanding operations into a right-to-work state finds that workers there can accept jobs on union projects without being required to join the union or pay dues, unlike the practice in the contractor's home state.
Who this matters most to
An HR Manager checks a new state's right-to-work status before assuming its existing union agreements and dues-checkoff practices will apply there the same way.
Where this goes wrong
An estimator prices a bid for a new-state project using the same union labor cost assumptions the company relies on at home, without checking whether the new state's right-to-work status changes union participation and effective labor availability there. The bid comes in based on assumptions that didn't actually hold in the new jurisdiction.