Boalt says they don't: http://www.law.berkeley.edu/admissions/jddegree/faq.html#Q3
Edit: I guess Boalt "strives for a majority of residents," but there's not a 50% quota, and "you have a roughly equal chance of being admitted regardless of your residency."
It's been awhile, but I definitely recall LSN suggesting an LSAT disparity between resident and nonresident admissions at Boalt during the 05-06 cycle. (All usual caveats regarding reliability of LSN data apply.)
Boalt's FAQ is an exercise in carefully worded ambiguity. Given that they get 6000-7000 applicants and enroll fewer than 300, they can legitimately claim "roughly equal" chances for both pools of applicants - that is, "small" and "slightly smaller." Even though they offer admissions to "equal numbers" of residents and nonresidents, they need not apply the same standards to arrive at those equal numbers.
Bottom line: there's circumstantial evidence suggesting that in-state students do have an advantage at Boalt, but nothing like a "50% quota."
I believe that UT Austin has an in-state quota, although I can't find it on their website.
Yeah, nonresident enrollment is limited to 35%, though as I understand it, that's measured over a period of years rather than for each class.