"disproportionate sentencing" is correct and can be used in written English.
You can use it when you want to refer to a situation in which someone is being punished more severely than would normally be expected for a particular offense. For example, "Many people feel that the judge gave a disproportionate sentencing for the crime committed."
Such wildly disproportionate sentencing clearly violates the Eighth Amendment's ban on cruel and unusual punishment.
The state of federal law regarding recidivist sentencing, and disproportionate sentencing in general, is in fact quite unclear.
The prime minister has faced criticism for this stance, with MPs, lawyers and campaigners warning against "disproportionate" sentencing.
Biased juries, insufficient evidence and disproportionate sentencing have become a key feature of the way in which Muslim suspected terrorists are treated.
The wildly disproportionate sentencing of young digital activists suggests that there's something the US government and associated nation states are anxious to deter.
In the US, disproportionate sentencing has become the norm and our Supreme Court has expressly held that it reserves judicial intervention to extreme examples like "life in prison" for a parking violation (Michigan v. Harmelin, Kennedy, J. concurring).
Jamel Dossie, meanwhile, is serving what Judge Gleeson called an onerous and disproportionate sentence.
British and American officials were quick to condemn what they described as a "disproportionate" sentence.
Braxfield's biased conduct of the trials and the disproportionate sentences handed out had provoked consternation at Westminster.
Judge Advocate's Recommendations: The Army Judge Advocate, Allan R. Browne, pointed out the inadequate and disproportionate sentences to the instances of beatings.
They had been exercising their democratic right to protest, they said, but had been made to feel the force of the law and receive "harsh and disproportionate sentences".
