Shooters and Fishers Party MPs have backflipped on their decision to vote against the government's controversial plan to abolish the right to silence.

After spending several hours in a government briefing on Wednesday the two MPs, Robert Borsak and Robert Brown, voted in support of the government bills, giving the government the numbers it needed to pass them.

One law will abolish the right to silence, allowing juries to draw an adverse inference if people accused of a crime chose not to take part in police interviews, but later relied on evidence they did not disclose.

The other law will make it compulsory for the defence and prosecution to outline their cases weeks before trial, to prevent the prosecution from being surprised by arguments. If the accused raises a different defence at trial, the judge could instruct the jury to draw an unfavourable conclusion.

A spokesman for the Shooters and Fishers Party MPs said "one day in politics is a long time".