Dyson has been unsuccessful in its push to change energy usage labelling laws in the EU because it failed to demonstrate more reliable and accurate tests than the ones currently used.
The company has alleged that many vacuum cleaners are advertised as having a lower power rating than they actually consume in real-world situations.
This is because while the advertised rating may be true when the device is empty, as soon as it fills with dust the power requirements can double.
The EU's General Court said: "Dyson states that the regulation misleads consumers because the cleaning performance is tested only when the vacuum cleaner's receptacle is empty and not during use.
"The court acknowledges that the suction performance and energy efficiency of a vacuum cleaner with a dust-loaded receptacle will be reduced due to dust accumulation.
"It observes, however, that the (European) commission could not use tests conducted on the basis of a dust-loaded receptacle, as they are not reliable, accurate and reproducible, as required by the regulation."
The court also dismissed Dyson's claim that current EU energy labelling laws "discriminates" in favour of bagged vacuum cleaners.
The appeal from James Dyson and his company follows accusations against Bosch and Siemens that their vacuum cleaners drew far more power than was advertised.
BSH Home Appliances, which owns both companies, later said it was taking legal steps against Dyson following the accusations.
Ukip MEP Margot Parker, the party's small business spokeswoman, said: "It is sad to see the European Court of Justice strike down a fair and reasonable complaint with such ease.
"Evidently the form of testing used does not allow for an equal evaluation of different types of vacuums. Unfortunately for Sir James Dyson, he has found himself on the end of yet more anti-competitive, bureaucratic and ill-conceived European regulation."