What was the primary motive behind president franklin d roosevelt's 1937 proposal to add members to the supreme court?

On February 5, 1937, President Franklin Roosevelt announces a controversial plan to expand the Supreme Court to as many as 15 judges, allegedly to make it more efficient. Critics immediately charged that Roosevelt was trying to “pack” the court and thus neutralize Supreme Court justices hostile to his New Deal.

During the previous two years, the high court had struck down several key pieces of New Deal legislation on the grounds that the laws delegated an unconstitutional amount of authority to the executive branch and the federal government. Flushed with his landslide reelection in 1936, President Roosevelt issued a proposal in February 1937 to provide retirement at full pay for all members of the court over 70. If a justice refused to retire, an “assistant” with full voting rights was to be appointed, thus ensuring Roosevelt a liberal majority. Most Republicans and many Democrats in Congress opposed the so-called “court-packing” plan.