Dozens of protesters began a sit-in at the court today in anticipation of the verdict.
The lower house of parliament was dissolved last summer after the Supreme Constitutional Court ruled against its constitutionality.
On 22 November, President Mohamed Mursi issued a constitutional declaration making Egypt's constituent assembly, tasked with drafting a new constitution and Shura Council (Upper House) immune from dissolution and steeling his decisions against judicial appeal.
Earlier, the court had to suspend work after Islamists sieged it to prevent it from dissolving the Upper House of parliament.
This came after the Egyptian president had issued a constitutional declaration to immunise the upper house from dissolution, just as the lower house had earlier been dissolved by the SCC.