This is what it says, and this is what Article 10.2 of the ECHR is about. The words "restriction" (for "límite") and "freedom of expression" are those used in the official English version of the Convention so I suggest they should be used here.

I think it would mean the same if you said "explicitly establishes as a restriction on freedom of expression".

"ARTICLE 10
1. Everyone has the right to freedom of expression. [...]
2. The exercise of these freedoms, since it carries with it duties and responsibilities, may be subject to such formalities, conditions, restrictions or penalties as are prescribed by law and are necessary in a democratic society, in the interests of national security, territorial integrity or public safety, for the prevention of disorder or crime, for the protection of health or morals, for the protection of the reputation or the rights of others, for preventing the disclosure of information received in confidence, or for maintaining the authority and impartiality of the judiciary."
http://www.hri.org/docs/ECHR50.html#C.Art10

So maintaining the authority and impartiality of the judiciary is one of the factors that can justify restricting freedom of expression, according to the ECHR.

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Note added at 1 hr (2013-03-11 00:31:04 GMT)
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Just read Edward's note on my answer, so of course I must reply. There is no redundancy here. What your text says is

"la autoridad e imparcialidad del Poder Judicial, que el art. 10.2 del Convenio Europeo de Derechos Humanos erige en límite explícito a la libertad de expresión"

This means:

"the authority and impartiality of the judiciary, which Article 10.2 of the European Convention on Human Rights establishes as an explicit restriction on freedom of expression".

"Límite", restriction, must be included, otherwise the point being made is lost, and the syntax doesn't make sense.

Article 10.2 does, as a matter of fact, establish the ways in which freedom of expression may legitimately be restricted. Article 10.1 establishes freedom of expression as a general right.

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Note added at 3 hrs (2013-03-11 01:59:22 GMT)
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It's not just that Article 10.2 establishes restrictions on freedom of expression, not freedom of expression itself (as the ST says), it's also that "erige en" means "establishes as", not just "establishes".

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Note added at 5 hrs (2013-03-11 03:43:48 GMT)
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I really don't understand the point Edward is making about a double negative. Establishing a right is one thing. Establishing a restriction on a right is another. Both are perfectly straightforward concepts. The fact that a particular form of words doesn't occur in an Internet document doesn't mean it's wrong, and is not a reason for choosing a form of words that does appear but is wrong. As a matter of fact, examples of "establish explicit restrictions/limitations" can certainly be found, as you would expect. But that is not in itself relevant. And I'm sorry, but "the authority and impartiality of the judiciary, which Article 10.2 of the European Convention on Human Rights explicitly establishes freedom of expression" is not only not quite different from what the source text is saying, but doesn't actually make sense.

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Note added at 5 hrs (2013-03-11 03:45:32 GMT)
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Sorry: I meant to say "is not only quite different" in the last line.

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Note added at 1 day1 hr (2013-03-11 23:36:29 GMT) Post-grading
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It's a pleasure, Richard. Very glad it was helpful.