"The Court is most vulnerable and comes nearest to illegitimacy when it deals with judge-made constitutional law having little or no cognizable roots in the language or design of the Constitution"

This quote by Byron White speaks to the importance of the Court sticking to the language and design of the Constitution when making decisions. White is recommending that when the Court makes decisions based on judge-made constitutional law, which has little or no basis in the language or design of the Constitution, it is vulnerable to illegitimacy. This is because the Court is not following the original intent of the Constitution, and is rather depending on its own interpretation of the law. White is stressing the value of the Court staying true to the language and design of the Constitution, as it is the only way to ensure that the Court is making decisions that are legitimate and in line with the original intent of the Constitution.