Blue Fox, a subcontractor, was not paid by the prime contractor on an Army construction project and tried to collect directly from the government using an equitable lien. The Supreme Court ruled that sovereign immunity prevents subcontractors from enforcing liens against the federal government, even under the Administrative Procedure Act. This means subcontractors cannot bypass the Miller Act bonding requirements to recover unpaid amounts directly from government agencies.
Always require the prime contractor to post a Miller Act payment bond before starting work on federal projects—this is your primary protection if the prime contractor fails to pay you.
You cannot sue the federal government directly for an equitable lien if the prime contractor doesn't pay you. Your only remedy is the payment bond.