Key legal question
Whether the claim against the canton must be judged under federal private law or Vaud state liability law
Extracted holding
Because the canton was performing a public task in highway construction, liability against the canton itself was governed by public-law state liability rules, not by general private-law claims.
Extracted reasoning
A canton is generally liable for harm caused by its officials only under public law, unless a specific federal exception or a genuine commercial activity applies. Constructing an interurban tunnel for the national road network was a public task, not a commercial activity. The procurement context did not create a general private-law liability of the canton toward an unsuccessful bidder or a third party.