Rule of law
Looking for independent evidence (i.e. other than the claim referenced in the OP), there are the "Worldwide Governance Indicators" from the World Bank, which include a measure of "rule of law".
The Rule of Law PDF is an overview of how they measure "rule of law". It includes not only "independent judiciary" but many dozens of other measures including:
- Extent of crime
- Speed of justice
- Compensation for state expropriation
- Intellectual property rights
- The public's trust in the system
- Tax evasion
- Whether there's a "parallel economy"
- Whether court orders are enforced
- etc. etc. etc.
It seems to be a sliding scale (not a boolean measure) from more to less rule of law. You can't easily say, "these have it and these don't".
The dataset/spreadsheet shows:
- The usual suspects i.e. the Scandinavian countries are at the top of the list
- The usual suspect i.e. Somalia at the bottom of the list
If I sort all countries in the spreadsheet by their 2013 "Rank" score, then the following are in the top 50:
- NEW ZEALAND
- JERSEY, CHANNEL ISLANDS
- UNITED KINGDOM
- HONG KONG SAR, CHINA
- UNITED STATES
- AMERICAN SAMOA
- FRENCH GUIANA
- TAIWAN, CHINA
- CZECH REPUBLIC
- SAN MARINO
- KOREA, REP.
- CAYMAN ISLANDS
Countries that are not in the top 50 include
- Greece (78)
- Italy (81)
- India (101)
- China (128)
- Russian Federation (160)
On the subject of (specifically) judicial independence instead of (more generally) rule of law:
The UN Basic Principles on the Independence of the Judiciary says that it was,
Adopted by the Seventh United Nations Congress on the Prevention of Crime and the Treatment of Offenders held at Milan from 26 August to
6 September 1985 and endorsed by General Assembly resolutions 40/32 of 29 November 1985 and 40/146 of 13 December 1985
I think that implies that the General Assembly at least pays lip service to an "independent judiciary".
There's an International Covenant on Civil and Political Rights signed by virtually every country.
Article 14 of this says,
All persons shall be equal before the courts and tribunals. In the determination of any criminal charge against him, or of his rights and obligations in a suit at law, everyone shall be entitled to a fair and public hearing by a competent, independent and impartial tribunal established by law. The press and the public may be excluded from all or part of a trial for reasons of morals, public order (ordre public) or national security in a democratic society, or when the interest of the private lives of the parties so requires, or to the extent strictly necessary in the opinion of the court in special circumstances where publicity would prejudice the interests of justice; but any judgement rendered in a criminal case or in a suit at law shall be made public except where the interest of juvenile persons otherwise requires or the proceedings concern matrimonial disputes or the guardianship of children.
So the prima facie evidence is that virtually all countries have (or claim to have, or agree to have) an independent judiciary.
The World Bank's Governance Indicators referenced above use the Cingranelli Richards Human Rights Database and Political Terror Scale (CIRI) for its measure of judicial independence.
CIRI measures judicial independence on a scale of from 0 to 2.
- 0= 50+ violations (least respect for human right)
- 1= 1-49 violations (some respect for human right)
- 2= 0 violations (full respect for human right)
Data was collected from 1981-2011 for the respective countries and each unit is referred to as a "country-year". A country-year is a single snapshot of space and time for the given country. Other variables, such as the political rights indicators, are scored based on respect for the human right by the same scale, with 0 indicating the least respect and 2 the most respect. The CIRI database uses the annual country reports from the US State Department and Amnesty International as its primary sources.
If I sort that database then the following 65 countries are rated "2":
- Antigua and Barbuda
- Cape Verde
- Czech Republic
- Korea, Republic of
- Marshall Islands
- Micronesia, Federated States of
- New Zealand
- Papua New Guinea
- Saint Kitts and Nevis
- Saint Lucia
- Saint Vincent and the Grenadines
- San Marino
- Solomon Islands
- South Africa
- Trinidad and Tobago
- United Kingdom
- United States of America
I conclude that the "only 40" claimed in the OP is untrue, or uses who-knows-what standard of measurement, or ignores smaller countries from its count, as well as not counting countries like the Bahamas, Greece, Italy, Singapore, and Taiwan, which for whatever reason only scored a "1" (i.e. neither "2" nor "0) on the CIRI report.