A MELBOURNE woman has won the right to appeal her welfare fraud charges to the High Court, which could affect thousands of others charged under the same law.

Kelli Keating, 36, worked casual shifts that varied from week to week when she failed to declare changes in her income to Centrelink between 2007 and 2009.

Last year, the single mother was charged with welfare fraud after she received overpayments of $6942.

The Social Security and Other Legislation Amendment (Miscellaneous Measures) Bill, which came into effect last year, makes it a criminal offence from March 2000 to fail to report any changes that could affect Centrelink entitlements within two weeks of them occurring.

Victoria Legal Aid, representing Ms Keating, challenged the law, saying it was unconstitutional because it retrospectively criminalised such behaviour, and interfered with judges’ ability to determine the law at the time of the offence.