Robert P. George is the McCormick Professor of Jurisprudence at Princeton University. He was interviewed by the National Review recently regarding the Terri Schiavo case. His comments are worth a careful reading.
There are a number of circumstances in Schiavo's case (i.e. her wishes, the cause of her injury, her ability to be rehabilitated) that have been debated by the media, Michael Schiavo, and the Schindlers. None of these 'unknown's' are relevent as to whether her medical care should be terminated. Michael Schiavo is pursuing her death, because he feels her life is of no value. There is no legal precedent that makes this a valid reason to take a life. In fact all human life has value, and this country was founded with Life as a guiding principle.
What we do know, what is agreed upon by all parties, is that the Schindlers are willing to pay for Terri's care, and that she has commited no crime.