"should have granted" is correct and usable in written English.
It is used to express regret for something that did not happen in the past. For example: "The company should have granted us more time to finish the project, but they were impatient."
The Scots are outraged that Jack Straw, the home secretary, should have granted the boxer, a convicted rapist, an immigration visa.
The state court, the dissent said, should have granted Glossip's request for a new evidentiary hearing to investigate his claim of innocence.
Indeed, Facebook probably should have granted more restricted stock units, as it gets the benefit of a much larger tax deduction than if it had issued restricted stock.
The Ohio Supreme Court should have granted a stay of execution, which it wrongly denied shortly before the governor stepped in because of the trial court's finding.
The Court of Appeals for the Sixth Circuit reversed, holding that, in the light of the First and Fourteenth Amendments, the District Judge should have granted the respondents' motion for a directed verdict as to all the Cantrells' claims.
Having made such a determination, the Court of Appeals held that the District Judge should have granted the motion for a directed verdict for respondents as to all the Cantrells' claims.
The Court therefore should not have granted the petition in the first place, or it should have dismissed the writ as improvidently granted as soon as oral argument made manifestly clear the insufficiency of the record.
The groups, claimed that the city should never have granted Mr. Gunther a zoning variance for the project.
He might decide that the Supreme Court should not have granted certiorari, or heard the case, in the first place – the "buyers' remorse" analysts have been talking about.
But if the Court was dissatisfied with the scope of the questions presented here it should not have granted certiorari in this case.
In court papers, Mylan described the F.D.A.'s actions as "arbitrary, capricious and unlawful" and said the agency should not have granted Ranbaxy the sole right to sell the drug.
