Although that concerned another subject-matter—printed news dispatches—we agree that, if it meant to lay down a general doctrine, it would cover this case; at least, the language of the majority opinion goes so far. We do not believe that it did. While it is of course true that law ordinarily speaks in general terms, there are cases where the occasion is at once the justification for, and the limit of, what is decided. This appears to us such an instance; we think that no more was covered than situations substantially similar to those then at bar. The difficulties of understanding it otherwise are insuperable. We are to suppose that the court meant to create a sort of common-law patent or copyright for reasons of justice. Either would flagrantly conflict with the scheme which Congress has for more than a century devised to cover the subject-matter.