Job Sikhala, a 50-year-old firebrand, has languished in a Harare maximum security prison since June, when he was arrested along with other opposition activists on charges of inciting public violence.
In a political career spanning more than two decades, Sikhala has been arrested 67 times but never convicted, according to one of his lawyers. He has unsuccessfully applied for bail 10 times.
His latest bid was denied in November by a magistrate who described the lawmaker as an "incorrigible unrepentant criminal".
On Wednesday, the high court in Harare reserved judgment indefinitely on an appeal filed by the parliamentarian's lawyers.
"I need more time to study judgments made against the appellant by previous courts," said the judge, Samuel Deme.
Sikhala's lawyers said it was highly unlikely there would be another ruling before Christmas.
Sikhala was held on June 14 along with fellow opposition politician Godfrey Sithole over a speech he gave at the memorial service for another opposition activist whose mutilated body was found in a well days earlier.
Fourteen other opposition activists were also arrested after clashing with ruling party members at the funeral.
All but Sikhala have since been released.
There is rising discontent in Zimbabwe as President Emmerson Mnangagwa - who replaced long-time ruler Robert Mugabe in 2017 following a military-aided coup - struggles to ease entrenched poverty, end chronic power cuts, and rein in inflation.
Rights groups and opposition parties have complained of an increased government clampdown on dissent as the country heads towards general elections next year.