Former DoJ attorney John Carlin writes about hackback, which he defines thus: “A hack back is a type of cyber response that incorporates a counterattack designed to proactively engage with, disable, or collect evidence about an attacker. Although hack backs can take on various forms, they are—­by definition­—not passive defensive measures.” His conclusion: As the law currently stands, specific forms of purely defense measures are authorized so long as they affect only the victim’s system or dat…