On April 23, 1950, Mexico seized five United States fishing boats which she claimed were violating her 9-mile territorial limit. Owners of the vessels paid under protest an administratively levied fine of 5,000 pesos per boat, after which their property was released.
The United States protested the action by means of a formal note delivered by Ambassador Thurston to Acting Foreign Minister Manuel Tello on May 4. The note in part reiterated United States recognition of a 3-mile, rather than a 9-mile, limit. (Enclosure to memorandum from Mr. Mann to Mr. Miller, May 4, 611.12/5–450)[Page 947]
Documents in file 611.126 for 1950 indicate that Departmental officers considered a variety of further responses to the incident. However, both the Bureau of Inter-American Affairs and the Office of the Legal Adviser discouraged any action that would bring a case before an international tribunal on the ground that, the 3-mile limit not being universal, the United States might lose. Reluctance to proceed was perhaps also related to both the claim of the United States to natural resources of the continental shelf and its designation of certain contiguous areas of the high seas as fishery conservation zones.
Additional legal uncertainties were: whether the United States had previously recognized the Mexican 9-mile limit in certain Gulf areas by its own past actions, whether the vessels in question could be proven to have been outside the 9-mile limit, and whether to take this last consideration into account (i.e., whether to initiate a broad or a narrow action).
Departmental officers also considered the additional alternatives of bilateral or multilateral negotiations to resolve fishery and/or territorial issues, but no action was taken along these lines during 1950.
The file mentioned contains further information.