Glad to hear the operative word here, “former”.
Check it out:

Former Supreme Court Justice John Paul Stevens, in his new book, recommends six rewrites to the U.S. Constitution. He would restrict gun ownership to militia members; ban the death penalty; and allow government to set “reasonable limits” on campaign financing, among other things.

But Stevens says he’s no radical:

One of Steven’s proposals would add five words to the Second Amendment, which would then read: “…the right of the people to keep and bear arms, when serving in the militia, shall not be infringed.”