Vicky Pryce's solicitor says she may appeal
Economist Pryce was convicted last week of perverting the course of justice by taking speeding points for then husband Chris Huhne, the former cabinet minister.
Both began eight-month jail sentences on Monday.
Vicky Pryce's solicitor questioned whether she should have been treated as a victim rather than a defendant as he indicated an appeal was still being considered.
Speaking to Today presenter Justin Webb, Robert Brown also cautioned critics of the "marital coercion" defence unsuccessfully used by Pryce that they could leave victims of domestic abuse defenceless if it was removed.
The case has led to widespread demands for the "arcane" coercion defence - which applies only to wives - to be scrapped.
Mr Brown said the law needs updating, but explained: "There are still cases where there are women in relationships where they are vulnerable and they may be put under pressure to commit crimes and they need the state to be able to defend them rather than just prosecute them."
"We shouldn't forget ... that it is Government policy and it is part of the CPS policy, that domestic violence is not confined to physical violence; it includes the application of pressure, specifically, and coercion, specifically."
First broadcast on BBC Radio 4's Today programme on Wednesday 13 March 2013.