"dubious legitimacy" is a correct and usable phrase in written English.
You would use it to describe something that you question or doubt the validity of. For example, "She finished the race in first place, but her win had a dubious legitimacy, as she had been caught cheating."
These approaches are of dubious legitimacy and will worsen global inequities.
But the trial of Mr. Sharif was itself of dubious legitimacy.
The Mamlūk sultans of Egypt, under whom the country thrived for several centuries, established a pseudo-caliphate of dubious legitimacy.
Mr Kostunica says the Hague court is a political affair, biased against Serbs, and of dubious legitimacy.
For months, well before the election, M23 protested against the Wade regime and in particular the dubious legitimacy of the president's bid for a third term.
The United States will rightly try the first person accused of conspiracy in the Sept. 11 attacks in an American courtroom, before a civilian jury, and not in some hastily assembled military tribunal of dubious legitimacy.
Through its pro-settler policies, Israel is forging one political entity between the Jordan River and the Mediterranean Sea — an entity of dubious democratic legitimacy, given that millions of West Bank Palestinians are barred from citizenship and the right to vote in the state that controls their lives.
While the Abe administration dominates both houses of the Japanese parliament, it is uncertain of its ability to revise the constitution rapidly and critics view the new interpretation as one of dubious political legitimacy.
In this, Bosnia is an image of Europe's future: ungovernable populations, exhausted by austerity measures and left to their own devices after the collapse of remnants of the welfare state – a state with no prospect for growth, run by elites of dubious, if any legitimacy who deploy heavily armed police to protect themselves against ordinary citizens.
This isolation from the state, lack of positive interaction between frontline public sector organisations such as the Police and the community leave the door wide open for organised criminals and extremists to advance their dubious morals and legitimacy in a community under pressure surrounded by a hostile and suspicious society.
Now that Mrs Gandhi has the legitimacy, however dubious, of being the first of her family to win a party election, the feeling is that the next order of business will be to start causing the government trouble.
