The phrase "already existing rules" is correct and usable in written English.
It can be used when referring to rules that are currently in place or have been established prior to a certain point in time.
Example: "Before implementing the new policy, we must consider the already existing rules that govern our operations."
Alternatives: "currently established rules" or "pre-existing rules".
"There already are existing rules for data transfer between Europe and third-party countries like the United States," said Luca Schiavoni, a telecom regulatory analyst based in London with Ovum, a technology consulting firm.
Some municipal governments have already tinkered with existing rules to admit only "desirable" outsiders.
Here Cameron did better, although only because Tusk clarified, in effect, that all these things are already covered by existing rules and principles.
Semi-automatic firearms resembling weapons with automatic mechanisms would also be banned under the Commission proposals, just as automatic weapons are already banned under existing rules.
Existing rules already require such plans for sites larger than five acres.
Existing rules already require that food labels indicate whether any genetically modified organisms are present.
Though the new rules, for example, might seem to apply to foreign news organizations in China, existing rules already restrict global media outlets from posting content on the Internet using servers inside China.
The rules will impact the way bonuses are paid in the City as the Financial Services Authority has already warned that its existing rules, which currently cover 27 firms, will have to expand to cover up to 2,500 firms which operate with in the square mile, Canary Wharf and the hedge fund land to the west in Mayfair.
Other EU leaders could turn round and say that the Court has now made it clear that the UK (and others) can already do that under existing rules.
Existing rules already provide for low payment costs between euro zone countries.
