I'm not even finished with it, and I'm recommending Jodi Picoult's My Sister's Keeper

Here's a snippet from Booklist's review:
Thirteen-year-old Anna Fitzgerald walks into the office of lawyer Campbell Alexander and announces she wants to sue her parents for the rights to her own body. Anna was conceived after her older sister, Kate, developed a rare form of leukemia at the age of two, and has donated bone marrow and blood to her sister. Now she has been asked to donate a kidney, and she intends to refuse. Campbell is a jaded young man who nevertheless decides to take her case pro bono. Anna's parents are shocked when they learn of her lawsuit, and her mother, a former civil defense attorney, decides to represent them. Anna refuses to budge on her position despite the fact that she clearly loves her sister and longs for her family's happiness. As the gripping court case builds, the story takes a shocking turn. Told in alternating perspectives by the engaging, fascinating cast of characters, Picoult's novel grabs the reader from the first page and never lets go. This is a beautiful, heartbreaking, controversial, and honest book.