Mr Justice Tugendhat will give his decision on the meaning of an allegedly libellous tweet she sent after a Newsnight report that wrongly implicated the Tory peer in child sex abuse allegations.
Earlier this month the judge reserved his decision in the case.
If the judgment goes in Lord McAlpine's favour, there will be another hearing at a later date on the appropriate level of damages, unless the two sides reach a settlement.
More top news
Around 40% of workers admitted to working despite being too sick for the office, a survey has revealed.
High street stores con customers by offering "discounts" which offer little to no savings - and may end up costing more, Which? has claimed.
Britain has claimed victory over Germany in a special football match marking 100 years since the near-legendary WWI Christmas truce match.