In Note, ‘The “Probable Cause” Requirement for Search Warrants’, Harvard Law Review, 46.8 (1933), 1307–1311 https://doi.org/10.2307/1331624, the following text appears:
The exact limits which the Fourth Amendment places on the power of Congress to provide for the issuance of search warrants have never been satisfactorily determined. Within recent years, however, there has been a noticeable tendency to regard the constitutional requirement of "probable cause" and the statutory test of "probable cause to believe", prescribed by the National Prohibition Act, as synonymous. At the same time, warrants for smuggled goods, issued merely upon "cause to suspect" in accordance with the present Tariff Act, have been sustained as an "exception", because the Collection Act of 1789, passed more than two years before the Fourth Amendment was ratified, contained a similar provision.
What is the distinction between "probable cause to believe" and (probable) "cause to suspect"? I can't understand the difference. The article goes on to imply that "probable cause to believe" is a stricter, harder-to-achieve standard than the previous conception of "probable cause."
By the way, I searched the Volstead Act for the phrase "probable cause to believe," and it doesn't seem to appear, so I don't know what the author's talking about there either.
: 41 STAT. 308 (1919), 27 U. S. C. § 11 (1926).