How re-write without negativity? 'may never directly prohibit private party actions, this does not mean that it cannot have horizontal direct effects'

Solution 1:

Don't even try. This is a law text. The slightest change to its meaning would be fatal. And even if you managed to modify the text correctly, the existence of two different versions is at least confusing.

To me, the "negativity" as you call it is one hundred percent necessary to express exactly what is meant. As an example, "may never directly prohibit" is not the same as "can just sometime indirectly prohibit". Not at all. Actually, it means something totally different. The first statement is about direct prohibition, the second about indirect prohibition. Totally different things. And the suggestions in the other answers have the same problem, they significantly change the meaning of the text.

Solution 2:

The sentence was a negative statement - it needs a negating word

There is actually no way to preserve the meaning of the original legal text without using a negating word or a using a construction that negates one of its clauses, simply because the meaning of the sentence was that the two things it talks about are not linked.

Secondly, there's no grammatical transformation you can do on this sentence to remove those negating words, because the sentence is a type of logical formula that cannot be inverted.

Grammar problems: expressing that two things are unrelated

Don't be thrown by the presence of if: this sentence is not expressing a conditional relationship. In fact, the information being conveyed here is the opposite: that the two clauses describe independent things, even though they may seem related at first glance. To see this more clearly, let's condense the two long clauses so we can see the structure of the sentence better.

Let X be the statement "an (unimplemented) directive may never directly prohibit private party actions [PPAs]"

... and let Y be the statement "it [a directive] cannot have horizontal direct effects [HDE] in civil disputes challenging the legality of State actions"

Now the sentence looks like this:

• "if
  • the Court wishes to say X
• this doesn't mean that
  • Y"

That's pretty simple isn't it? If this was mathematical logic, we could also say "X does not imply Y", or using the mathematical notation for such things:

• ~(X→Y)

The squiggle means "not" (or "is false"), the arrow means "implies".

Logical problems: inverting implications

So, why am I talking about logic? Because knowing a little bit about logic is important if you want to avoid the mistake that a couple of answers have made.

If "X implies Y" (or "X does not imply Y"), one cannot simply negate the two clauses X and Y and still have the sentence mean the same thing. Here's the famous example:

• X = "the animal is a dog"
• Y = "it has four legs"
• (X→Y) = "if the animal a dog, this means that it has four legs"

Now, invert the clauses X and Y:

• ~X = "the animal is not a dog"
• ~Y = "it does not have four legs"
• (~X → ~Y) = "if the animal is not a dog, this means that it does not have four legs"

Okay, that's plainly nonsense (consider cats), so let's invert the implication too:

• ~X = "the animal is not a dog"
• ~Y = "it does not have four legs"
• ~(~X → ~Y) = "if the animal is not a dog, it does not mean that it does not have four legs"

Incidentally, we've now arrived at the structure of the orignally-quoted sentence (it's almost like I went back and changed my examples!). But, have a look at where we are and where we came from:

• ~(~X → ~Y) = "if the animal is not a dog, it does not mean that it does not have four legs"
• (X→Y) = "if the animal is a dog, it means that it has four legs"

These two sentences don't mean the same thing at all. The first sentence says nothing about animals that are dogs, the second says nothing about animals that are not dogs.

That's the problem: implications can't be negated in the way that simple statements of fact can. You need to re-word the sentence.

However, in the original sentence the "X does not mean Y" is the most important idea being conveyed, so you really need to leave it in place.

Solution 3:

Answer coming from somebody well-versed in the principles of EU law, such as direct effect.

(1) I don't think just sometimes indirectly is an improvement to never directly. You still have a negation (it's in the prefix in-), but you have more words. Moreover, I think it does not precisely reflect the meaning of the original. It would rather be something along the lines of:

For if the Court simply wishes to say that an (unimplemented) directive might prohibit PPAs indirectly, at most.

The crucial point is that the alleged court statement does not make a definite assertion about whether indirect prohibitions are legally possible. It just denies direct prohibitions.

(2) The same for (2). It's not quite accurate. The original sentence does not say for certain that HDE is possible. It just says that impossibility is not a necessary conclusion from (1). In other words – we don't know if HDE is possible here, but we know that (1) is not a reason that makes it impossible.

That being said, HDE is an established principle and would apply here, according to how I understand the author.