A member of Stormont's standards committee has called for the assembly's code of conduct to be broadened.
Green Party leader Steven Agnew said it was too easy for MLAs to claim they were not acting in their capacity as elected representatives when responding to complaints.
Mr Agnew's call comes in the wake of a report by the Stormont standards watchdog which cleared NI21 leader Basil McCrea of a range of serious allegations, including sexual misconduct and voyeurism.
However, Stormont's standards committee said the manner in which Mr McCrea occasionally treated his staff fell short of the standard they would encourage.
Mr McCrea claimed the allegations were a conspiracy to force him to resign.
In standards commissioner Douglas Bain's report he cited a number of situations where the Lagan Valley MLA was said not to have been acting in his "capacity as an elected member of the assembly". These included an occasion when Mr McCrea spoke at a Sinn Féin summer school in Cork.
It was during the June 2013 trip that the NI21 leader is alleged to have groped the bottom of female party worker Jacquelyn Neglia. The commissioner concluded that on the basis of the evidence, he could not be satisfied "on the balance of probabilities" that Mr McCrea behaved in the manner alleged by Miss Neglia.
Both Mr Bain and the assembly's standards and privileges committee concluded that Mr McCrea did not undertake the speaking engagement in his "capacity as an elected member of the assembly".
The report includes other instances where the NI21 leader is said to be acting in a private capacity, including a trip to Canada and a discussion he had at Stormont with a party employee.
But according to Mr Agnew the remit of the code which Mr Bain is enforcing is too narrow.
"I have consistently argued that the scope of the assembly code of conduct should be extended," the North Down MLA told The Irish News.
"Currently it is too easy for MLAs to claim they were not acting in their elected capacity in order to have allegations of a breach of the code dismissed – I think it is reasonable that the public expect MLAs to adhere to certain standards."
Mr Agnew said the code should not be limited to "attending formal assembly business but also when they are participating in public or political events".
"Like all citizens, politicians have a right to a private and family life, however, at public engagements or even party events I believe that MLAs should be subject to the standards of the code of conduct," he said.
"Our public duty does not stop and start and the doors of Stormont."
