Most RPS programs require obligated utilities or suppliers to demonstrate compliance through renewable energy certificates, each representing the environmental attributes of one unit of qualifying renewable generation, tracked through state or regional registry systems; disputes commonly arise over certificate double-counting, fraud, or disqualification after the fact, which can retroactively create a compliance shortfall.

Most programs also set an alternative compliance payment as a price ceiling a supplier can pay in lieu of acquiring certificates, and disputes over how that payment is calculated or whether it satisfies the underlying statutory mandate are a recurring feature of RPS litigation. Separately, some RPS programs favoring in-state generation resources have faced dormant Commerce Clause challenges alleging impermissible discrimination against out-of-state renewable generators, and disputes over whether specific resources — such as large hydroelectric facilities, existing nuclear plants, or renewable natural gas — qualify as RPS-eligible generation are common and can materially affect compliance costs.

Because certificate markets and eligibility rules can shift after a supplier has already made procurement commitments, retroactive eligibility and registry disputes create a distinct compliance-risk profile from ordinary contract litigation. A Juricratic simulation can model certificate-eligibility risk and alternative-compliance-payment exposure as separate dials to rehearse a supplier's total compliance cost range across plausible regulatory outcomes.

RPS compliance disputes typically arise when a regulator finds a shortfall in a supplier's certificate holdings, when a generator's resource eligibility is challenged or revoked, or when an in-state preference in the program design is challenged as unconstitutional, with resolution often occurring through commission enforcement proceedings or federal court litigation over the constitutional question.