O2's battle with Hutchison 3G ended in the European courts
Mobile phone operator O2 has lost a four-year court battle with Hutchison 3G over the use of its bubbles trademark in advertising.
In 2004 Hutchison used the bubbles in a campaign for its "Threepay" service comparing its prices with O2's.
The case had been referred to the European Court of Justice to decide.
The European court ruled that firms could use competitors' trademarks in comparative advertising if there is no risk of customer confusion.
The judges said that four conditions had to be met if a trademark owner was to prevent the use of imagery similar to its own.
It must be used within the course of a trade, without consent, in respect to similar goods, and in a manner likely to cause confusion.
Though Hutchison had met three of the criteria, it had not satisfied the last.
Hutchison 3G said the decision was "great news for consumers across Europe" and "pro-consumer and pro-competition".
"This ruling clears the way for us to put our deals up against the best our competitors can offer and let the consumer decide," said company sales and marketing director, Marc Allera.
The case had been taken to both the UK High Court and the Court of Appeal before being referred to the European Court of Justice.
O2 uses oxygen bubbles against a blue water background as its trademark across its marketing material.