A member of the council governing the Bar Association, Erik Shum, alleged on Thursday that the government is using arbitrary standards when barring people from running for Legco seats.
"There is no such local legislation in the Legco ordinance to the effect that there is scrutiny or any disqualification provision as to political inclination. It is not there," Shum said.
Returning officers have rejected Demosisto candidate Agnes Chow and localist Ventus Lau from running in the March 11 by-elections.
Speaking to the media after taking part in online programme with former lawmaker Emily Lau, Shum said such disqualification is a most serious violation of one's political rights.
The barrister also questioned the returning officers' duties and their limits. According to Shum, an officer's job is to check the nomination forms, including a declaration form which says the candidate will uphold the Basic Law after getting elected.
To vet a candidate's brain and find that he is not sincere in giving that declaration is something nobody can do, including a returning officer, he said.
Shum also said that the newly elected Bar Council held talks with Justice Secretary Teresa Cheng on Wednesday and raised the issue of Chow's disqualification, as well as the controversial plan for a joint immigration checkpoint at the West Kowloon express rail station.
He described the meeting with the secretary as "very amicable".