It would help if you gave a short explanation of what the NDAA is. I realize it may be something I don't know about since I'm not American, but still, I'm interested.
Sorry about that. The National Defense Authorization Act (NDAA) is a bill that is passed every year and appropriates funding for military expenditures.
This year, there are clauses that legislatively codify the President's authority to indefinitely detain terrorism suspects, including American citizens, without trial.
The govt. has been claiming that capability under the Authorization for Use of Military Force Against Terrorists (AUMF) already, but Congress has always been vague and handwavy about supporting it. This codifies and effectively rubber-stamps the process, saying "We approve"