Bilateral investment treaties typically require the host state to ensure "fair and equitable" treatment to the investors of the other state.
Verrill, Charles Owen Jr.
"Are WTO Violations Also Contrary To The Fair And Equitable Treatment Obligations In Investor Protection Agreements?,"
ILSA Journal of International & Comparative Law: Vol. 11
, Article 1.
Available at: http://nsuworks.nova.edu/ilsajournal/vol11/iss2/1