After somewhat abstract introduction, they give some concrete examples as well (in the collapsible boxes), e.g. from CETA:
“A Party breaches the obligation of fair and equitable treatment referenced in paragraph [previous] if a measure or series of measures constitutes:
(a) denial of justice in criminal, civil or administrative proceedings;
(b) fundamental breach of due process, including a fundamental breach of transparency, in judicial and administrative proceedings.
(c) manifest arbitrariness;
(d) targeted discrimination on manifestly wrongful grounds, such as gender, race or religious belief;
(e) abusive treatment of investors, such as coercion, duress and harassment; or
(f) a breach of any further elements of the fair and equitable treatment obligation adopted by the Parties in accordance with paragraph [next] of this Article.
The Parties shall regularly, or upon request of a Party, review the content of the obligation to provide fair and equitable treatment. The Committee on Services and Investment may develop recommendations in this regard and submit them to the Trade Committee for decision.” (CETA, Article 8.10, paras 2-3)
The obligations in paragraph [X] to provide:
- “fair and equitable treatment” includes the obligation not to deny justice in criminal, civil or administrative adjudicatory proceedings in accordance with the principle of due process embodied in the principal legal systems of the world; and
- “full protection and security” requires each Party to provide the level of police protection required under customary international law.
A determination that there has been a breach of another provision of this Agreement, or of a separate international agreement, does not establish that there has been a breach of this Article.
For greater certainty, the mere fact that a Party takes or fails to take an action that may be inconsistent with an investor’s expectations does not constitute a breach of this Article, even if there is loss or damage to the covered investment as a result.
For greater certainty, the mere fact that a subsidy or grant has not been issued, renewed or maintained, or has been modified or reduced, by a Party, does not constitute a breach of this Article, even if there is loss or damage to the covered investment as a result.” (TPP, Article 9.6)
The legalese is quite broad, as you can see. It's more important who enforces it. As more [in]famous examples they give Philip Morris v. Uruguay and (the lesser known) Philip Morris Asia Limited v. Australia. These were adjudicated in different courts: the latter by the Permanent Court of Arbitration at The Hague (note that it's not a UN body); the former by the World Bank's ICSID. Both suits took years. Who has jurisdiction depends on the treaty, of course.
For a [somewhat] comparative overview of the common arbitration venues for such matter (including the above two), see for example this page of a specialized law firm (It's a bit too long to quote all that here.) One intersting bit from there is that ICSID seems the most often used venue.
For a more general overview see Wikipedia's page on investor-state dispute settlement (ISDS). A few interesting bits from that page:
ISDS cannot overturn local laws (unlike the World Trade Organization) which violate trade agreements, but can grant monetary damages to investors adversely affected by such laws. [...]
According to the International Bar Association (IBA), states have won a higher percentage of ISDS cases than investors, and that around one-third of all cases end in settlement. Claimant investors, when successful, recover on average less than half of what the amounts claimed. IBA notes that "only 8 per cent of ISDS proceedings are commenced by very large multinational corporations." IBA challenges the notion that ISDS is biased against developing countries, noting that there is "no correlation between the success rates of claims against states and their income levels or development status."
A 2017 study found that the success rates of investors in investor-state disputes has sharply fallen over time because most legal challenges today seek compensation for regulation implemented by democracies, not expropriation by non-democracies. The author of the study argues that the likely goal of investors is not to obtain compensation through ISDS, but to impose costs on governments contemplating regulations and therefore deter the regulatory ambitions of governments.
There's also a discussion of transparency rules for proceedings (or lack thereof; these rules were improved relatively recently) and accountability for the judges/arbitrators. Of the sample cases discussed there, Occidental v. Ecuador seems the highest award given to a company ($2.4 billion). Wikipedia fails to mention that the award was later reduced to "$1 billion plus interest". Although fairly recently decided, this was more of traditional case (in terms of the 2017 paper):
The 2012 decision said Ecuador’s seizure of an oil block operated by Occidental was “tantamount to expropriation.”
For a more exensive analysis of this case see https://doi.org/10.1093/icsidreview/sit021, which by the way appears in a specialized journal for such cases. A more recent (2015) paper confirms that it was the largest award granted by ICSID till then.