It's extremely variable. The book allowance is generous even if buying new, and if you buy used &/or sell &/or use the library you can get by on a fraction.
Rent will run from under $500 (looking at you, Jeffersonian) to as much as you want to spend. You don't need a car if you live on Arlington and if you live on the east coast even travel expenses are minimal.
Still, if you're thinking about how many loans to take out, it makes sense to take the max every semester. Then whenever you want you can re-pay loans without penalty, even if it's the day after disbursement. It's a bit more work but it gives you a lot of control and avoids a situation where you run out of money.
On that note, everyone should have and learn to responsibly use a CC while in law school. Building a credit history and good credit score will save you money down the line - you'll get better rates on loans / mortgages that you're very likely to want at some point in your life, and length of credit history is one of the most important factors in your score. Plus it gives you float if you screw up your finances or have an emergency between loan distributions.
Extra credit: apply for a credit limit increase while working for a firm over the summer. Most companies only care about your take home pay, and even if you tell them it's a temporary job you still will likely qualify for an absolutely ludicrous credit limit. Another credit score factor is percentage utilization. It's only a minor over simplification to say that a higher credit limit will always mean a higher score.
And if you ever need to flee the country on short notice, it gives you more ability to lever up first
"A fake passport, 6 pounds of caffeine powder, 25 pounds of Grade A beef jerky cutlets, a book of dick jokes, 4 Radeon 6990 graphics cards, and a 1200 Watt power supply. Then they never saw him again. What happened to the man known as thesealocust. In what deep recesses of his mind did he formulate a plan that involved these things, and then vanish in to the night? Tonight, America, we will seek those answers"
NBC Network Transcript
Date Line NBC, February 21st, 2017.