The American Bar Association requires that law schools use an "admissions test" as part of the admissions process. Although the LSAT is the test of choice, there is no reason why it has to remain so. For example, the GRE is now being used as along with the GMAT as part of the admissions process for many some MBA programs.

What would be an alternative to the LSAT?

Read the following article.
http://lawschool.about.com/b/2008/11/17/looking-beyond-the-lsat-report-released.htm

It references a report that may be found here:
http://www.law.berkeley.edu/beyondlsat/

Additional discussion:
http://www.law.com/jsp/article.jsp?id=1202425850913

Although this is interesting, it is probably a long way away.

Richardson - LSAT - GMAT - GRE - MCAT Preparation Courses - Toronto, Canada
http://www.prep.com