Under international human rights law, some limits on freedom of expression are allowed. Does this mean that any restriction is permitted? Only if it passes the “three-part test” of legality, legitimacy and proportionality.
These are criteria that come out of Article 19 of the ICCPR. Recall what Section 3 says about restrictions:
… these shall only be such as are provided by law and are necessary: (a) For respect of the rights or reputations of others; (b) For the protection of national security or of public order (ordre public), or of public health or morals.”
“provided by law”
The government must follow a written law that is clear and not ambiguous. Otherwise, people won’t know when and how they might be accused of doing something wrong.
“(a) For respect of the rights or reputations of others; (b) For the protection of national security or of public order (ordre public), or of public health or morals.”
These are the only legitimate grounds for restricting speech. It is supposed to be a complete list, and not a “for example” list that states can add to. Any restriction must pass this legitimacy test.
Note that the following common reasons that governments give for censorship are not regarded as legitimate:
“For making the government’s job easier”
“For maintaining respect for the country’s leaders”
“For stopping lies and irresponsible views”
Because freedom of expression is a right that must be upheld as much as possible, restrictions should be applied only when really necessary. Punishments must be proportionate. If not, they will create a fear of speaking up, which should not be the case. An example is defamation. It is recognised as a legitimate reason to restrict speech; but it is not necessary to treat it as a crime that could lead to the imprisonment of the defamer. Instead, it should be a civil matter, requiring apologies, retractions and payment of reasonable damages.
You may wonder about the “national security” rationale, which is often given as an excuse by governments that simply want to silence their critics. Because of this potential for abuse, it is important that the government doesn’t get to test itself. Instead, independent courts should be the ones deciding whether the government is passing the three-part test.
To go really deep into this question of how the ICCPR’s Article 19 should be interpreted, you refer to this UN Human Rights Committee General Comment published in 2011.