CBC reports that suspended senator Patrick Brazeau was arrested overnight in Gatineau, Que.
The Canadian Press has not been able to independently verify the reports that Brazeau is in custody.
Gatineau police spokesman Pierre Lanthier said only that a 39-year-old man was arrested after a 911 phone call about a domestic incident.
"It was an altercation between a man and a woman," he said.
He said the man could face charges of assault, possession of drugs, breach of undertaking and uttering threats.
He said officers who went to the scene found that an altercation had taken place on a patio in front of a residence.
A woman complained of being assaulted by the 39-year-old.
Brazeau already faces a number of legal problems.
In February, the RCMP charged him with fraud and breach of trust in relation to his Senate expense claims.
In another legal case, Brazeau is charged with assault and sexual assault, over an incident at his home in February 2013.
A year ago, the Senate ordered Brazeau to pay back almost $50,000 over disputed expense claims. He refused, and the Senate garnished his salary until last November, when he was suspended without pay.