"could only be justified" is an acceptable and grammatically correct phrase that can be used in written English.
You can use it when you want to express that something is reasonable or appropriate in a given situation. For example, "The decision to close the school early could only be justified by the extreme weather conditions."
Returning items or negotiating with cultural communities about their use are forms of reparation, and could only be justified within a library framework as works of justice.
And it was likely to be a gamble that could only be justified if the prize was the capture of Godane, the al-Shabaab eminence grise.
The leader of the opposition in Parliament, Christian Jacob, said afterward that an intervention "could only be justified in the framework of the United Nations".
The Bishop of Oxford, the Rt Rev Richard Harries, warned the prime minister that any military action against Iraq could only be justified if there was a fresh UN resolution.
"The resolution is concerned with the protection of civilians, so a military attack on Gaddafi's retreating forces could only be justified if it could be shown to be related to that objective," he said.
Add to that the puppeteers and brilliant voice artists like Harry Enfield, Kate Robbins and Steve Coogan – you had an insanely complex and expensive operation that could only be justified because it was regularly watched by more than 10 million people.
By full-time, home concern had only been justified.
Second, dedicated procurement policies are hardly free market and could only be really justified in the face of extreme distortions in procurement practice caused, for example, by discrimination.
Our trust or distrust may be prima facie justified if we have the correct default stance, although most philosophers assume that it could only be fully justified either by reasons that are internal to us or by the causal processes that created the attitude in the first place.
An opinion commissioned by Google from the Danish judge Bo Vesterdorf, a former president of the European court of first instance, claims such an obligation could only be legally justified where a company has a duty to supply its own rivals.
Applying this in the context of Syria, the violation of the prohibition on the use of force could only be fully justified if it would cause less harm to the legal system than the harm caused by allowing the use of chemical weapons to go unpunished.
