The federal government has secured a big win over big tobacco with the High Court ruling Labor's world-first plain packaging laws are constitutionally valid.
The legal victory means all cigarettes and tobacco products will have to be sold in drab olive-brown packs from December.
Large graphic health warnings will dominate the packs and the manufacturers' brand names - such as Camel or Winfield Blue - will be written in a small generic font.
Although the court handed down its decision on Wednesday the reasons for judgment won't be revealed until later in the year.
British American Tobacco, Japan Tobacco International, Philip Morris and Imperial Tobacco Australia argued in April that plain packaging was unconstitutional because it "extinguished" their brands and logos without compensation.
But the commonwealth insisted it had the right to regulate cigarettes just like other products harmful to human health, such as rat poison, which require warnings about safe handling.
Attorney-General Nicola Roxon is expected to hold a press conference soon to discuss the court's ruling.