A new Victorian MP has used his first speech to call for drug possession to be decriminalised, arguing billions of dollars of taxpayers’ money is being wasted on failed policies of prohibition.

Liberal Democrats upper house MP David Limbrick also paid tribute to his federal counterpart Senator David Leyonhjelm, who is being sued for defamation by Greens senator Sarah Hanson-Young for alleged "slut-shaming" comments.

The balance of power in Victoria's upper house is held by 11 crossbench MPs. Credit:Joe Armao

A self-described libertarian, Mr Limbrick vowed he “would never vote for a reduction in freedom or an increase in taxes”.

One of two Liberal Democrats elected to the upper house in November, he received just 0.84 per cent of the vote in the south-east metro district but secured a favourable preference deal from "preference whisperer" Glenn Druery.