The phrase "arguably unfair" is correct and usable in written English.
It can be used when discussing a situation or decision that may be considered unfair, but there is room for debate or differing opinions on the matter.
Example: "The new policy is arguably unfair to employees who have been with the company for many years."
Alternatives: "potentially unjust" or "possibly inequitable."
Because he knew to expect a Branca fastball, Thomson had an arguably unfair edge.
The charge is arguably unfair: the firm's health coverage, while admittedly less extensive than the average for big companies, is on a par with other retailers'.
It is arguably unfair to review a place that so recently opened, but I like to see what is going on early on as the restaurant invents itself.
If true, that would mean the judgement is arguably unfair — and that is why in two weeks' time the court could be in the unprecedented position of having to reopen the case.
While this view is arguably unfair, it is equally unjust to decree that gay people, no matter how committed, faithful or enduring their relationships may be, are unable to attain this standard.
In effect, he was on his own, set free to wobble, fall and get up again when faced with an unfamiliar, and arguably unfair, salvo of public criticism from Charles Barkley and Magic Johnson.
Yet simply using the four year graduation rate is arguably highly unfair to schools that accept students with mediocre academic records, lower cognitive skills, etc.
So, in what is arguably an unfair test of a car designed mostly for short-distance motoring, the BBC decided to try to drive an electric Mini the 484 miles (778km) from London to Edinburgh.
Arguably this was unfair to the spectators; if the result had been more important he surely would have played.
I travelled the country, documenting more than a hundred cases in which people's property was seized on mere "suspicion" of wrongdoing, or through other arguably unconstitutional or unfair means.
Arguably, it is unfair to exclude racers with disabilities on the ground that crude prosthetics render unable to be competitive, and then also to exclude them when better prosthetics make them highly competitive.
