It’s interesting to see the remarks of Gerald Ford on signing the first ‘fast track’ bill:
http://www.presidency.ucsb.edu/ws/?pid=4849
And Of President Reagan on signing the 1984 ‘fast track’ bill:
http://www.reagan.utexas.edu/archives/speeches/1984/103084c.htm
Until NAFTA ‘fast track’ probably did more good than harm.
Since then nothing but loss seems to have come from it.
Fast track is neither unconstitutional or an inherently bad thing. Depends on the negotiator. The present negotiator needs to be given fast track authority like I need another 10 years added to my age.