Neither the Amsterdam or the Maastricht treaties are no more than ratifications of existing protocols, expansions, new agreements and deletions of old outdated ones.
You must read the individual laws and exceptions on a particular law.
Article 45 of the TFEU (ex Article 39 TEC)
1.Freedom of movement for workers shall be secured within the Union.
2.Such freedom of movement shall entail the abolition of any discrimination based on nationality between workers of the Member States as regards employment, remuneration and other conditions of work and employment.
3.It shall entail the right, subject to limitations justified on grounds of public policy, public security or public health
I am unfortunately intimately familiar with the subject. I rather I would not be.