1.Your study group is not the Section 4 Supper Club.
Figure out from the start whether you and the other members of the group are looking to form a serious study group, or are mostly just interested in some structured socialization. You're in a new school, a new city, odds are you didn't know anyone when you showed up, and so it's easy to turn to study groups for socializing.
So, because you are lukewarm, and neither hot nor cold, I will spit you out of my mouth.
You don't want a bunch of Chatty Cathies getting your studying off schedule, and you don't want a bunch of Gunner Gretchens ruining happy hour with shop talk. A hybrid study/social group will fail at both aims. If you want a social group, join one of the many other organizations, or start an unofficial XYZ University Law School Drinking Club.
2. Divide and be conquered.
Some study groups like to divide up the work. You outline for this class, I'll outline for the other. It makes sense, from a strictly economics point of view.
As a matter of prudence, it is incredibly risky. You're putting your faith and trust in someone who you've only known for a few weeks. You don't know how reliable they are, or even if they're a good student. You can agree to trade notes and outlines with other members of your class, but this should only add to the work you've done your self; it shouldn't take the place of it.
It's fine to concentrate more on the class you've agreed to outline for, but when deciding how much work to do for the other classes, always keep in mind the chance that the other members of the group may fall through. You have no recourse if a member of your group decides to join another group and take his notes with him.
3. Stop worrying about the curve, you suck at math anyways.
One of the first questions people have about joining study groups, sharing notes, and preparing for exams together, is how they should view the group in light of the class's curve. After all, you're competing for the same limited number of As, and if you get just as much help as you give, aren't you really just back at square one?
No. Also, you're an idiot if you think that, so kiss your A goodbye and start praying you don't get a C.
If the entire class were in the same study group, then you'd have no real gain. But, if your study group is just 4 people out of a class of 100, then helping three other people doesn't really mess the curve up for you. The benefit you receive more than offsets the damage to the curve.
4. Consider how your class is graded.
Other than being a mediocre social club, there are two main things your study group can do. The first is to help you prepare for class, meeting weekly to discuss the readings and make sure everyone understands everything before getting cold called. The second function is to prepare for the exam.
If class participation does not count towards your grade in the class, reconsider how much time you spend preparing on a week to week basis, and especially how much time you spend in your study group. It would be boneheaded to put off all your reading until the end of the semester, but as a law student your time and energy are limited. It may not seem like the law studently thing to do, but you need to shift your mental resources towards classes graded for class participation.
If your study group doesn't have their priorities sorted out, you may be better off going on your own.
5. You will be asked to cheat.
If you are in a study group for a class with a take home exam, there is a very good chance that the idea of collaborating (aka: cheating) will come up. It will be subtle, maybe someone wondering aloud about whether other study groups are doing it, but rest assured, it will come up.
We're not going to decide for you what you should do. Not cheating is the "right thing to do." But, there's also the question of whether you should turn in the other members of the group if you suspect they cheated without you.
And, there's also an argument to be made in favor of cheating. You are graded on a curve, and your grades, especially your first year grades, will have a huge impact on the course of your career. The professor has created an exam which he knows or ought to know is incredibly susceptible to cheating. About 45% of law students will cheat at some point, and you can bet it's more likely to be on a take home exam than an in-class open book exam.
In a perfect world, it would be easy to not cheat. You'd feel little pressure to cheat, think it unnecessary, and cheating would be hard to do. But, a tenured professor went and created a scenario that fosters cheating, and ultimately penalizes students for not cheating by measuring their grades against the grades of cheaters. A lot of the blame falls on him for creating such a bad situation in the first place, just as God shares some of the blame for creating the Tree of Knowledge in the first place, and not putting a dang fence around it. Attractive nuisance.
The question is which are you more willing to let slide, your morals or your career aspirations? It's a tough call, but just remember, cheat with people you've smoked pot with, they're less likely to rat.