A recent Montana Supreme Court decision on agency law reminds us once again to ensure all intended parties to an agreement are actually parties and not simply agents acting for another party in the transaction. Big Sky Civ. & Envtl., Inc. v. Dunlavy, 2018 MT 236, 2018 Mont. LEXIS 329 is a case in point. Architect representing the project owner engages an engineer on behalf the owner. Payment of invoices becomes and issue. The engineer, thinking he is engaged by the architect sues the owner, the architect and the principal partner of the design firm. The Court granted judgment for the architect firm and its principal–stating that an agent (architect) dealing with third parties (engineer) on behalf of disclosed principal (project owner) has no liability absent an agreement to the contrary. Two lessons: 1) use specific written engagement agreements every time. The email chains between the firms containing the contract terms lacked any evidence that responsible party was anyone other than the owner; and 2) State who is footing the bill. If you expect the from the agent or the agent and the principal, name them specifically and their obligations clearly.