The Federal Government will know the fate of its plain packaging laws for cigarettes today.

The High Court is today set to hand down its landmark decision on the future of the laws, which were passed by Federal Parliament in November.

The new laws would require cigarettes to be sold in olive green packs.

They were set to be introduced in December, but that now depends on a constitutional challenge mounted by the major tobacco companies including British American tobacco, Philip Morris, Imperial Tobacco and Japan Tobacco.

The companies say the Government is trying to acquire their intellectual property, including trademarks, without proper compensation.

But the Government says it is only trying to regulate what appears on the boxes and is not acquiring any trademarks.

The case is being watched carefully, with other countries considering similar laws.