No.
A degree cannot hurt, but you might want to do a little research before you commit to a course of study.
As was stated, I also have a BA in Admin of Justice. It is good for the job app, but has very little real world use for me. In fact, I am currently getting my graduate degree in Art (which I love,) and the fact that all my undergrad work was in CJ is hurting me. I have to pretty much start from scratch and shell out some serious $$$ for my prerecs. If I could go back, I would have picked a program that had a little more potential for advancement.
Most departments do not require a degree, but pay some nice incentives for previous education. 15% in my dept! Thats some good $$$ over a career.
As far as most departments, a degree is a degree. Art, Crim, Basketweaving are all the same as far a s incentives and pre-employment qualification. Pick something you WANT or LIKE to do in case you choose to persue a graduate degree. Don't get too wrapped up in the "we'll give you credit for all your police training" degree plans...unless all you want is the degree for the money (which is fine, too.) BTW, I know a few guys and gals that have taken their CJ degrees to the graduate level for teaching and such...so don't think I'm saying the program is totally useless.
Finally, a degree will definately help you promote. It just looks good on paper. I am stating the obvious when I say that a degree does not equate to being a good cop, but a paper trail when It comes to promotion time (if that is your goal) will help.
Good luck!
NorCal