First, I want to apologize for running a group where each player is a rules lawyer. Talk about a DM's worst nightmare.
Second, you do have some options here. Try talking to them, explain to them that you are new and you are learning as you go. This might work for some but maybe not all, and the ones it doesn't work on (which are the same people that never give any DM's any slack at all) will only make it worse. Talk to them as a group, or one on one.
After talking to them, pick the lawyer you feel most comfortable with (wow, talk about your oxymoron right there)

and have that one person your rules sage/lawyer for any rules questions you may have. Basically this person should be used for advice and advice only when you need to make fair decisions based on circumstances. It will be obvious if they try to take advantage of you, so be prepared.
Tell them that even though you are a new DM, you are still in charge and you will be fair, but lay down some ground rules before the next session begins. If something comes up during a game that requires a rule check, say you will read the rule and make the decision, and that decision stands. You could be nice and give them two minutes to state their reasoning, but that's all they get, and to emphasize this buy a stop watch and time them. Then make your decision, stick with it, don't budge and AFTER the game review it and if you ended up making a rather bad decision, apologize and learn and move and don't dwell on it.
If after all this doesn't work, do what the rest of the world does. Shoot all the rules lawyers and follow all guidelines in The Slayers Guide to Rules Lawyers published by Mongoose.

That book as some great advice also.