In most cases heard concerning the 8th amendment rights, what punishment has been an issue

Capital punishment

Explanation:

The punishment that has generally been an issue when it comes to the 8th Amendment is that of capital punishment. The 8th Amendment prohibits the application of "cruel and unusual punishment," and many people believe the death penalty to be an example of cruel and unusual punishment. This is supported by the fact that most countries do not tolerate the death penalty. Moreover, the countries who do tend to be considered unjust or undemocratic.

My guess would be the death penalty