Why is Lincoln's signature on the 13th amendment?

[tbaked]

Just watched the movie and this thought came up. I thought the President has no role in the constitutional amendment process.

http://answers.yahoo.com/question/index?qid=20110327161639AAYuUxr
http://www.archives.gov/federal-register/constitution/
http://wiki.answers.com/Q/Does_a_President_have_to_sign_an_amendment_into_law
As a modern parallel, it would be similar to President Obama signing the Supreme Court decision on the Affordable Healthcare Act, which would seem really out of place.

 

[JacksBrain]

Lincoln had his fingers in too many pies...