'has always been contested' is correct and usable in written English.
You could use this phrase when referring to something that many people have different opinions on and that has been debated over a long period of time. For example, "The morality of capital punishment has always been contested."
The legitimacy of strikes per se has always been contested by the employers and the state, because strikes represent a challenge to their authority, power, and interests.
They argue that a single national story is not a sound base for a common culture because it has always been contested by class, region and religion.
Until the legally enforced Cup 33 went the way of the San Francisco-based Oracle Racing when they beat the Swiss holder Alinghi in 2010 in giant multihulls, the America's Cup has always been contested in monohulls.
"Art" has always been contested terrain, whether the object in question is a medieval tapestry or Duchamp's Fountain.
Battleships were the largest and most complex, and hence the most expensive warships of their time; as a result, the value of investment in battleships has always been contested.
The production forest/convertible forest boundary has always been contested, especially as many "production forests" no longer have tree cover.
Until now, says Ghia Nodia, a political analyst, "power in Georgia had always been contested on the streets, while elections were simply a way of endorsing it".Contesting political power in an election still seems unorthodox to many Georgians.
And, despite the term's longevity, ideas about [End Page 15] who the Mountaineer is have always been contested and fluid.
Tracing the history of the term since its entry into the public lexicon in the nineteenth century, Jean-Christian Vinel demonstrates that the legal definition of "employee" has always been politically contested and deeply affected by competing claims on the part of business and labor.
Campaigners have previously estimated that only 6 percent of allegations of rape reported to the police resulted in a conviction for rape, but this widely cited figure has always been controversial, contested by the police and increasingly seen as part of the problem because it makes victims so cynical about the system that they decide not to press charges.
