There would be no need for the ACLU if people had the sense to learn and understand their rights, and if law enforcement and others learned their limitations. Unfortunately, few people bother. What can you expect from a country in which many high school graduates can't even find their country on a world map?
One of the great problems with living in a free society is that freedom requires a great deal of personal responsibility. Owning a gun is a right, and guns are extremely dangerous, a great deal of responsibility is required to possess a gun.
The freedom of speech is an even greater right, yet it is often abused. Speech is too often used to misinform or divide, rather than to inform or inspire. Words kill more people than guns; say the wrong thing to the wrong person, and the worst can happen.
Driving a car requires great responsibility, yet more than 40,000 Americans are killed in traffic accidents each year.
The ACLU has it's good and bad points, but if most Americans had a clue about their own laws and government, and how it works, the ACLU would be irrelevant. But, in a land where only 15% of registered voters bother to go to the polls, and where more than half the people can't name their local congressmen or state senators, the ACLU is necessary.