The Constitution can only be amended by the States, not Congress. Congress only ratifies the amendment after a majority of the states pass it. Alcohol prohibition pre-dates FDR's New Deal Commerce Clause. That's why it took a constitutional amendment to prohibit alcohol, but not for marijuana prohibition, which was done under FDR's Commerce Clause.
The Constitution can only be amended by the States, not Congress. Congress only ratifies the amendment after a majority of the states pass it. Alcohol prohibition pre-dates FDR's New Deal Commerce Clause. That's why it took a constitutional amendment to prohibit alcohol, but not for marijuana prohibition, which was done under FDR's Commerce Clause.