EFTA countries are not subject to the ECJ
The author of the article - Frank Jennings - is a legal expert, but this part of what he says needs some clarification:
"With a Norway-style agreement, the UK would still be part of the EEA and would therefore have to comply with many EU laws, including the data protection ones – covering the new General Data Protection Regulation. In that case any law that potentially conflicts with GDPR – such as the UK Snoopers' Charter (aka Draft Communications Data Bill) – will be scrutinised directly by the EU Court of Justice and the UK will have to suspend non-compliant laws."
Norway isn't subject to the ECJ.
The court for the EEA agreement is the EFTA Court, not the ECJ. The ECJ has no jurisdiction over non-EU countries, including over EFTA countries. The EFTA Court was created expressly for this purpose.
It is true that the EFTA Court must take into account and in some cases directly follow ECJ case law (due to the 'principle of homogeneity' - NB according to the EFTA Court there is such a thing as 'creative homogeneity', and the EFTA Court mostly has to tackle fresh legal questions where there isn't case law'; also, the EFTA equivalent of the EU's Commission is not as eager as the EU Commission to bring legal proceedings so there are fewer cases at the EFTA Court), however one of the differences between the ECJ and the EFTA Court is that the EFTA Court has no power to fine the EFTA countries for non-compliance, whereas the ECJ does. Another is that the EFTA Court follows a different judicial style from that of the ECJ (the ECJ having elements of the French model).
EFTA countries have other, substantial advantages over EU countries.
For the UK to have a 'Norway-style agreement' is more or less code for 'If the UK rejoins EFTA' (the European Free Trade Association).
The EFTA was co-founded by the UK in 1960. EFTA members adopt approximately 10% of EU laws (not 'many', as Mr Jennings claims), and retain their sovereignty in all other areas. EFTA countries can freely enter into trade agreements with non-EU countries, either alone or via EFTA functioning as a group, as well as having access to the EU's 'Single Market'. This gives the EFTA countries far more agility, flexibility and strength than EU countries. They participate in things like EHIC and Erasmus, but they do so by free choice, they are not compelled by law.
EFTA isn't an ideal solution for the UK (there are no ideal solutions available to any country) but it is a massive improvement on being in a Customs Union (i.e. the EU), and a political project to create a new country out of the continent of Europe. Being in a Customs Union has meant that for 40 years the UK has not had an independent trade policy - we have had no sovereignty on trade policy for nearly half a century. If we'd stayed in EFTA, that wouldn't have been the case. We've also decimated our fishing industry; if we'd stayed in EFTA, that wouldn't have been the case either, as British waters would not have become Community waters (yes, that's right, there is no such thing as British waters anymore).
Some see rejoining the EFTA as providing a safer stepping stone out of the EU, on the way to a longer-term, ever better arrangement. The downsides in the EFTA-EU relationship are ones which Norway, Iceland, Switzerland and Liechtenstein would also like to change, and if the UK leaves the EU and rejoins the EFTA those changes become much more likely.
1 of 2. EUR-Lex website (official EU website of legal topics)
"European and international courts: There are many courts that operate at international level, and it is not always easy to distinguish their jurisdiction. The aim of this summary is to present the European courts and to distinguish between those which are part of the European Union and those which belong to other international organisations.
International Courts: There is a wide range of courts and tribunals that hear disputes at international level and which have their headquarters on European territory. However, these courts do not come under the auspices of the European Union. They are:
~ the courts of other European organisations, in particular the European Court of Human Rights and the EFTA Court (European Free Trade Association);
~ the courts created under the auspices of the United Nations;
~ the independent dispute settlement bodies of the United Nations.
Courts of other European organisations: Neither the European Court of Human Rights nor the EFTA Court is a European Union institution.
The EFTA Court enforces the Agreement on the European Economic Area (EEA)."
2 of 2. EFTA Court official website:
"The EFTA Court fulfils the judicial function within the EFTA system, interpreting the Agreement on the European Economic Area with regard to the EFTA States party to the Agreement. At present those EFTA States are Iceland, Liechtenstein and Norway."
"The EFTA Court has jurisdiction with regard to EFTA States which are parties to the EEA Agreement (at present Iceland, Liechtenstein and Norway)."