High-profile barrister Robert Richter KC said the most common ground was that the verdict was unsatisfactory and unreasonable.
"The Court of Appeal might find that it isn't sufficient to justify a conviction," he said.
"But that on its own is a very difficult ground to get home, because it sort of does not usurp the function of the jury, but what it does is it looks at what a jury ought to have concluded or should have concluded."
Mr Richter said if any of the directions given to the jury had misstated the law, it could be grounds for an appeal, but noted the judge presiding over the high-profile case had been "very careful".