The competition represents a desirable state of the market in every society. Putting a lot of effort in trying to be better than each other, the competitors of the market, where there is a fair competition, contribute to making that market more advanced than the other one with the weaker competition. However it has become quite frequent to come across the violation of the competition in modern society. It is usually done by making different agreements or with explicit or tacit coordination of conduct on the market. Apart from these, there are many other ways for doing so, with the aim of getting certain benefits, especially making extra profit. In addition to that, there are some restrictions on the competition on oligopolistic markets too, yet, those markets are covered with different market forms which cannot be easily distinguished from the forbidden ones. This paper defines the relation between the concerted practice and conscious parallelism on an oligopolistic market, which is the example of a restricted market conduct, and the one which just seems to be legal, according to the practice of the European Court of Justice.