It really depends where your interests lie. If you want to be a prosecutor then an MBA won't be much help. If you want to start your own firm or do business related litigation it might be an asset. I knew plenty of joint MBA/JD's at my school some were happy with their decision others were not. There is no right answer to the question, and it really depends on your goals and what you want.
As for the government job that is a very broad question what in government do you want to do? If it is securities regulation SEC then an MBA might be helpful. If you want to be a public defender it will be of little use. If your interested in your old position ask your old employer what he/she thinks they will know far better than any anonymous poster on the internet. .
I would like to add you Your legal education will be interfered with to some degree by getting an MBA, which should be considered. Another thing to be conscious of is do you really want to be a lawyer? You can just get an MBA, or find a job, many students go to law school without having any desire to be lawyers, and that usually doesn't go very well. Of course exceptions exist, but if you don't want to be a lawyer there are better ways to spend 100,000 and 3 years of your life. I'm not saying you don't want to be a lawyer, but many JD/MBA students that were dissatisfied with their decision didn't know whether they wanted to be lawyers or not. Just something to consider.
Good luck to you