Why isn't it mandatory for elected members of parliaments to have knowledge on the constitution?

Question

In most democracies, elected members of parliament are representatives of people who elect them. They are also supposed to pass laws, make amendments and perform other functions. Being representatives, they are supposed to do something for people, so that they be elected again or are in good books. But there is nothing to check how good they are with the constitution which they are supposed to protect and build on.

So I have the following questions:

• Why isn't it mandatory for elected members of parliament to pass a (written) test on the constitution before they give nomination?
• Are there any countries which have such a system?
• If none, is there some inherent issue with such a view?
• If some, do they have any advantage or disadvantage over the rest?

EDIT to add clarifications on question and to give a general gist of answers so far.

• As doubted by @Jonita this question doesn't assume constitutional law as the most important part of the constitution. The only intention was to find out whether such a system existed and if it did, check whether it had any advantage over the existing ones. If not, why. If such a system existed, I was hoping that system would have representatives who are more active in the building process of constitution by actively engaging in debates when new bills and amendments are presented in the house and thus making public aware of the same.
• @jamesqf has a nice point that it's assumed that people learn basics about constitution in school. Unfortunately, that too is not true. I am not sure how aware most elected members are about all these, let alone public. Then again, there aren't a lot of countries where they have 100% people completing (even) high school.
• @David Thornley mentioned, and quite rightly, that it's up to voters to decide about such a change. But as such a system doesn't exist (no one was able to provide evidence for one till now), how would voters even think about it? Till then it's a hypothetical system that exists in a few online threads.
• The biggest contribution so far was from @kevin and @James K, both convincing why such a test could be really a bad idea. But both had a predisposition that these tests have to be evaluated and according to the result, candidates should be disqualified. Instead of a test to disqualify, I gave a suggestion that candidates, before nomination, should do write up on topics which are given prior to nomination. There can also be a test, as @James K mentioned, which is taken by civil servants in some countries. None of the above has to be elimination criteria. Instead, it can be made available publicly so that public can go through it and have an idea about the candidates. This would mean the candidates cant just go with regular rhetorics and polarizing politics. Of course, they would still do it in other platforms. Another advantage is, as the material is publicly available, the public can go through these documents in the coming elections too. The above way to test candidates is just an opinion and I am sure there are other ideas, existing or new, that can be much more effective.
• In some countries judiciary has the power to review laws, as mentioned by @elliot svensson. But, that too is not mandatory for all laws.

Answer 1

Someone has to write the test.

The United States, in particular, has a long and sordid history of imposing "literacy tests" on voters. These were used to disenfranchise ex-slaves (and black people more generally) after the civil war (and continuing on for a century thereafter). The general approach was to exempt white people from the test, while requiring black people to follow confusing instructions, memorize long passages of text, and so on. Literacy tests generally were only federally outlawed in 1965 with the Voting Rights Act, so many Americans still remember the era in which they existed. Testing voters for literacy has an indelible taint of racism in American politics, and I think it unlikely that you would have much success introducing such a test for elected officials.

But more fundamentally, the problem is that it is impossible to write a neutral test. Consider the Second Amendment to the US Constitution:

A well regulated Militia[,] being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed.

The bracketed comma is not present in the version of the amendment which was passed by the Senate and the House, but is present in the publicly displayed version in the National Archives. So already we have two versions of this Amendment, both equally legitimate, and we haven't even begun to parse it.

This particular amendment has been interpreted in numerous ways by numerous different people. Here are some example interpretations:

• Each state has a right to operate a "well regulated" militia, because the people have a generalized right to defend themselves with guns which is implemented by giving the state a militia.
• Each state has a duty to operate a "well regulated" militia, and regular people should have guns in order to serve in that militia. States can even require people to own guns.
• Each state's militia consists of the (able-bodied) people (or men) of that state, who must be allowed to own guns in order to serve when the state calls on them.
• Militias are good, therefore people have a right to own guns just in case the state needs to form one.
• The US is not supposed to have a standing army for more than two years at a time, so regular people need to own guns in order to raise one or more state militias and/or a federal militia quickly in the event of invasion.

Several of the above interpretations merely claim that people owning guns is a "good idea," but others explicitly provide legal protection for owning a gun. Whoever is writing this Constitution test either needs to account for all of the above possible interpretations of this amendment (essentially removing all matters of interpretation from the test and relegating it to memorization of the literal text), or it needs to choose an interpretation (which is inherently political).

Of course, that's just the United States, which has the advantage of a short, written constitution with a well-defined amendment process. Contrast countries with no written constitution (the UK) and countries with very lengthy constitutions (India). In the case of the UK, a test might include such varied documents as the Magna Carta and an anonymous letter somebody wrote to the editor of The Times.

Answer 2

It's up to the voters. If the voters value knowledge of the constitution, candidates can use this as campaign material. If the voters don't care, why should there be a test?

Answer 3

This would have a negligible effect on the quality of governance. You are either testing knowledge that is easily available, or testing a skill that isn't required.

If you are in a country which has a written constitution, then knowing what the constitution says isn't difficult. Memorising it isn't a required skill. If you want to find out what the constitution says, just look at it online.

Interpreting the constitution may be harder. This is why when drafting laws, politicians use the services of lawyers, to check that the wording of a law is consistent with the constitution. There's no point in "testing" this. It's not the politicians’ job to be constitutional lawyers.

If the test was basic, this would be seen as insulting to many. Like asking a PhD mathematician to do a basic numeracy test. If the test was complex it would be irrelevant, like asking an accountant to demonstrate knowledge of analytic number theory.

In a democracy, this would be actively harmful. If the people have elected a person, their choice should not be negated on the basis of a test.

If your country doesn't have a written constitution, then deciding exactly what the constitution is can be a matter of debate.

Politicians are not selected by tests, however civil servants may be. In China, the UK and the EU, civil servants are chosen by competitive examination.

Answer 4

Assuming that a country's constitution is important, and believing that elected officials are powerful, I can see why it sounds like a problem that elected officials wouldn't necessarily understand their own constitution.

However, (at least in the US) this doesn't by any means result in a constitution that is toothless. On the contrary, constitutional authority is separate from elected officials and will exert pressure on them at the appropriate time whether they are prepared or not.

For instance, Trump's travel ban was reversed twice (if memory serves) by judges in the US–as far away as Hawaii!–because they deemed it unconstitutional. In addition, there have been 968 state laws to date according to this report that have been struck down because they were deemed contrary to the Constitution.

Summary

Not knowing the constitution doesn't remove constitutional protection from the public; but knowing the constitution will definitely make a legislator more effective in the long run!

Answer 5

The question assumes that Constitutional Law is the most important part of government. There's no reason for this to be the case.

Governments are also involved in;

Taxation
Trade
Education
Environmental Protection
Science
Military Defence

and an endless list of other activities without elected representatives having to be experts in all or indeed any of these fields. While constitutional law may affect and limit any of these other fields devising a sensible strategy for any of them requires knowledge in the specific area over Constitutional Law. That knowledge is generally held by advisers and the civil service rather than elected officials.

Any country that did require specific knowledge whether in Constitutional Law or any other area as a pre-requisite for office would be limiting the scope of its representation to a specific sub-set of society, when generally a broader range of experiences and background is useful in providing leadership to something with as many moving parts as a whole country.