This section is from the book "The Law Of Contracts", by William Herbert Page. Also available from Amazon: Commercial Contracts: A Practical Guide to Deals, Contracts, Agreements and Promises.
If the real principal X wishes to sue upon the contract, the parol evidence rule does not prevent him from showing that A was his agent and that X is the real party adversary to B.1 The fact that the contract is one of those required by law to be proved in writing does not prevent the principal from showing that he is the real party in interest, and enforcing the contract in his own right.2 A different principle applies if the contract is one of those which by law must be in writing.3 Questions involving the right of the adversary party to go outside the writing and hold the real principal thereon have been discussed elsewhere.4 The name of an individual signed to a contract may be shown to be the name of a partnership,5 but a contract signed by the names of two individuals cannot be shown to be the contract of a partnership composed of those individuals and others.6
1 New Jersey, etc., Co. v. Bank, 6 How. (U. S.) 344; Conklin v. Leeds, 58 111. 178; Harrington v. Foley, 108 la. 287; 79 N. W. 64; Tauton, etc., Turnpike v. Whiting, 10 Mass. 328; Elkins v. Ry., 19 N. H. 337; 51 Am. Dee. 184; Beebe v. Robert. 12 Wend. (N. Y.) 413; 27 Am. Dee. 132; Elkinton v. Newman, 20 Pa. St. 281; Belt v. Water Power Co., 24 Wash. 387; 64 Pac. 525; Coulter v. Blatchley, 51 W. Va. 163; 41 S. E. 133.
2 See Sec. 695.
3See Sec. 761.
4 As to contracts which are in writing, see Sec. 606, 607. As to contracts which must be proved in writing, see Sec. 695. As to contracts which must be in writing, see Sec. 761.
5 Butterfield v. Hemsley, 12 Gray (Mass.) 226.
6 New England Dredging Co. v. Granite Co., 149 Mass. 381; 21 N. E. 947.