thing is if it was unconstitutional, what can we do if supreme court says it isn't? They made some deal with them, probably bribes under the table. Or threats. I know wikipedia lies but it is interesting to see what the MSM account of history says:

As a result, the Court continued to enforce a Federal laissez-faire approach, overturning many of President Franklin D. Roosevelt's New Deal programs, which were designed to combat the Great Depression, by 5–4 margins. Most notably, the National Industrial Recovery Act was overturned unanimously in Schechter Poultry Corp. v. United States (1935), and the Agricultural Adjustment Act was struck down in United States v. Butler (1936).

In response, President Roosevelt proposed the Judiciary Reorganization Bill (called the "court-packing bill" by its opponents) in 1937, which would have increased the size of the Supreme Court and permitted the appointment of an additional justice for each incumbent justice who reached the age of 70 years and 6 months and refused retirement; under Roosevelt's proposal, such appointments would continue until the Court reached a maximum size of 15 justices. Ostensibly, the proposal was made to ease the burdens of the docket on the elderly justices, but Roosevelt's actual purpose was to pack the Court with justices who would support his New Deal policies and legislation. The plan quickly drew bipartisan opposition, including from Roosevelt's own vice president John Nance Garner, and it failed in Congress.[15][16]

Soon afterward, however, the ideological balance of the Supreme Court that had prevailed since Lochner began to shift. Justice Roberts, who had previously voted with the conservative bloc in invalidating New Deal legislation, began to vote on the opposite side. Roberts' decision spelled the end of the Lochner era and has been dubbed the "switch in time that saved nine." The balance of the Court shifted with the retirement of Justice Van Devanter 1937 and of Justice Sutherland the following year, while Justice Butler died in November 1939. By the end of 1941, Roosevelt had appointed seven Supreme Court justices and elevated Harlan Fiske Stone to chief justice.[17]

https://en.wikipedia.org/wiki/History_of_the_Supreme_Court_of_the_United_States#The_Hughes,_Stone,_and_Vinson_Courts_(1930%E2%80%931953)