Mate’s receipt is a document originally issued by the first mate of the ship, who is in charge for cargo operation. Then mate’s receipt or receipts collected by the shipper or his representative and later exchanged for a bill of lading, which should incorporate any qualifications or conditions inserted into the mate’s receipt.
Schuster v McKellar (1857) 7 El. Bl.704, per Lord Campbell, C.J.
It was admitted that, if the master and the brokers employed to superintend the load- ing of the ship had known that there was a mate’s receipt, it would have been their duty to have required the production of it, and to have attached it to the bill of lading. Their knowledge of it might well have been presumed, and was not negatived by any evidence.
Per Lord Wright in Nippon Yusen Kaisha v Ramjiban Serowgee  A.C. 429 at p.445:
The mate’s receipt is not a document of title to the goods shipped. Its transfer does not pass property in the goods, nor is its possession equivalent to possession of the goods. It is conclusive, and its statements do not bind the shipowner as do the statements in a bill of lading signed within the master’s authority. It is, however, prima facie evidence of the quantity condition of the goods received, and prima facie it is the recipient or possessor who is entitled to have the bill of lading issued to him. But if the mate’s receipt acknowledges receipt from a shipper other than the person who actually receives the mate’s receipt, and, in particular, if the property is in that shipper, and the shipper has contracted for the freight, the shipowner will prima facie be entitled, and indeed bound, to deliver the bill of lading to that person.
Naviera Mogor S.A. v. Société Metallurgique de Normandie (The Nogar Marin)  1 Lloyd’s Rep 412 per Mustill LJ at p.420:
… a mate’s receipt is in a quite different category from a bill of lading. No doubt the parties foresee that some such document will be signed. But the mate’s receipt is what its name indicates: an acknowledgment to the shippers that the ship has taken delivery of the goods. It is not part of the mechanism established by the charter-party, which does not stipulate that it is to be signed "as presented", or indeed at all. Nor does it share the prime characteristic of a bill of lading, of being a document which can be negotiated to third parties, thereby putting the shipowners into a new contractual relationship over which they have no control. It is a simple receipt. True it is, that if the mate or master signs it without qualification, it may put his owners into difficulties with the shipper who bails the goods into the custody of the ship, because it is prima facie evidence of receipt in good order and condition. But this creates no new liability, and no new party is involved. The master must choose for himself how to act, and the notion that if the charterer happens also to be the shipper he is in breach of duty under the charter-party by offering the master a document which, if carelessly signed by the master without proper enquiry, will constitute evidence in favour of the person who tenders it, is not a concept which we can grasp.