(to the below comment) Yes they did go after authors and redistributors of DeCSS, by arguing that it was a piracy tool. What I think is unlikely to happen, is

(to the below comment) Yes they did go after authors and redistributors of DeCSS, by arguing that it was a piracy tool. What I think is unlikely to happen, is anyone going after indiviual users who are using it to play DVDs, using provisions of the DMCA.