It used to be a common practice for Supreme Court Justices to dissent without writing an opinion. Today we would think that this was strange, and as far I can tell the change came around 1940 with the retirement of the “Four Horsemen” who opposed the New Deal. Why was this norm for judicial behavior abandoned?
First, prior to 1925 the Court did not have discretion over its docket. As a result, the Justices heard a lot more cases than they do now. Furthermore, many of those cases involved federal common law (torts, contracts, etc.) that were relatively unimportant. Under those conditions, people were probably more tolerant of a Justice who simply noted his position and saved the written opinions for important cases. Second, Justices in that era only had one clerk (or before that none). Thus, if a member of the Court was elderly or ill there would be every reason to think that he could not write. Today (though we don’t say so explicitly), there is a stronger expectation that such a Justice can still produce opinions.
Are there any other possible explanations?