A statutory maritime lien arises by operation of law when a vessel contracts for covered supplies and the supplies are delivered pursuant to the contract, regardless of whether the eventual provision occurred through a chain of intermediaries.
The subcontractor is operating pursuant to another's agreement with the party to the contract with the vessel, and therefore the subcontractor cannot assert a lien against the vessel.
Equitable remedies such as unjust enrichment are not a basis for a judgment against the vessel, as the lien is an in rem action.
Error for the District Court to issue a sua sponte summary judgment absent notice to parties where a reasonable possibility existed of a factual dispute.
http://www.ca2.uscourts.gov/decisions/isysquery/594b7f87-3c10-48a4-8c8c-42b1d446d0a8/2/doc/16-3923_opn.pdf#xml=http://www.ca2.uscourts.gov/decisions/isysquery/594b7f87-3c10-48a4-8c8c-42b1d446d0a8/2/hilite/
Since 2011. An occasional commonplacing of the U.S. Circuit Courts of Appeal.
Neither an authoritative statement of the law nor legal advice. Quick work.