Carillion confirmed that Dave Smith had been blacklisted but the tribunal ruled that as an agency worker he did not have the same rights as directly employed staff.
Smith launched the case using Human Rights legislation and vowed to appeal to Europe.
Outside the tribunal, he said: “The blacklisting conspiracy is a deliberate breach of human rights by big business.
“Human Rights are supposed to apply to everyone.
“If the British justice system does not protect workers rights, then we will be taking our case direct to the European Court of Human Rights in Strasbourg”