Fair and equitable treatment/Minimum standard of treatment, including denial of justice claims
Umbrella clause
National treatment
Customary rules of international law
Arbitrary, unreasonable and/or discriminatory measures
http://globalarbitrationreview.com/news/article/31712/hungary-wins-early-ruling-radio-dispute/ (requires subscription)
http://globalarbitrationreview.com/news/article/31370/hungary-knocks-part-radio-claim/ (requires subscription)