Where can i search the history of retroactive principle as a law? Thanks for the help...?

Answer 1

First - you need to limit your research - are you talking about U.S. law? Then you need to stay away from wiki sources. They have a nasty habit of being wrong.

Here are some starting points:

http://www.borrull.org/e/noticia.php?id=37322&id2=11607

http://socrates.berkeley.edu/~warcrime/ET-ELSAM-Reports/ELSAM01.pdf

http://books.google.com/books?id=nzQOAR5rqvcC&pg=PA304&lpg=PA304&dq=retroactive+principle&source=web&ots=QbFbPRs68p&sig=YGV_1XtzaC9ndrmXKTHIBrD3agA

http://rspas.anu.edu.au/pah/human_rights/papers/2001/Susanti.rtf

Answer 2

Any search engine, or you can start with wikipedia.

Look up "ex post facto" laws for a good starting point.