Any negotiation on the basis of land for peace is a fatal mistake.
MPs should be able to debate, amend and approve a mandate for the negotiation of any trade agreement before talks start, based on an independent impact assessment of what social, economic and environmental risks might be expected.
The first and pivotal negotiations over global access to AIDS drugs began in Geneva in 1991. They lasted two years, but confidential minutes suggest they were doomed the first day.
Everything is negotiable. Whether or not the negotiation is easy is another thing.
Usually, even when a bill draws extreme opinions, there can be a process of expression and negotiation.
Sanctions and negotiations can be very ineffective, and indeed foolish, unless the people you are talking with and negotiating with and trying to reach agreements with are people who can be trusted to keep their word.