Some criminals will always be dangerous even when they are released and in their cases prison sentences need to be made longer to protect society. However, if someone was wrongly convicted, then they shouldn't have to suffer through a long sentence. The entire justice system needs to be strengthened so that the people who deserve to be behind bars get longer sentences.
The United States could use a healthy dose of cutting back on its "Tough on Crime" stance. Our prisons are overflowing, and the reasons are purely political. Politicians just love "cracking down" on crime, and the war on drugs is the result. Now we have overcrowded prisons, house the highest percentage of our citizenry in jail, and have an antagonistic relationship between citizens and police. It's madness!
Longer prison sentences across the board won't do much to keep this country safe. Some sentences, such as nonviolent crimes concerning marijuana, for instance, should be shortened or reduced because all they really do is turn otherwise peaceful people into hardened criminals. Each case needs to be looked at individually rather than just imposing longer sentences.
Well this is a very broad question which I will side with No on in general. Think of yourself being imprisoned. Almost any length of time out of your normal surroundings not being able to live a normal life is going to feel like an eternity. If the length of current sentences are not going to rehabilitate the prisoner successfully, probably no length is going to.