Something to watch out as it could possibly impact the pound
The ruling is slated to be released at 0800 GMT as reported last week. On 4 December, a European court aide suggested that Britain could revoke Article 50 unilaterally, whereby it doesn't need any permission from other countries to cancel Brexit. That gave the pound a pop at the time but as mentioned, it's not something the government will be looking into exercising despite having the option; hence gains in the quid was faded eventually.
I would expect the ruling later to elaborate more on the details of the unilateral revocation and not offer much of anything new ahead of tomorrow's vote. However, best to stay alert in case for any surprises and reaction in algos/markets.
