'lacked justification' is correct and usable in written English.
You can use it to describe a situation where something has been done without any reasonable or logical grounds. For example: The CEO's decision to end the project was highly controversial as it seemed to lack justification.
Such a proposal lacked justification.
Rosenberg and coworkers caused an uproar in the immunotherapy community when they stated in a position paper that despite great advances in the field of tumour immunology, optimism about the clinical application of therapeutic vaccines lacked justification.
In Mr. Grasso's lawsuit, his lawyers assert that "Mr. Reed's and the stock exchange's campaign of disparagement lacked justification and that the Webb report did not provide a compelling basis for proceeding against Mr. Grasso".
The proposal, which revisits a 2011 rule limiting mercury emissions from coal plants, argues EPA lacked justification to curb the neurotoxin in the first place because many benefits stemmed from the overall drop in air pollution that would occur once power companies adopted new technologies.
"It's been our position all along that police lacked justification to arrest and detain Martese," Watkins told the AP.
The disregard of SEM test evidence lacked justification, though the flawed arguments discussed above camouflaged the disregard of troubling evidence for decades and permitted the evidence-disrespect to spread surprisingly widely.
In a word, he lacks justification.
Although Westway's defeat has been derided as lacking justification, Westway's critics raised substantial and ultimately decisive objections.
It follows that, according to the convergence view, those liberal commitments will lack justification.
The fact that our beliefs cohere can establish their truth, even though each individual belief may lack justification entirely if considered in splendid isolation, or so it is thought.
It is not just that we lack justification for accepting a general hypothesis as true only on the basis of positive instances and lack of counterinstances (which was the old problem), or to define what rule we are using when accepting a general hypothesis as true on these grounds (which was the problem after Hume).
