The West Australian government’s decision to slug a Clive Palmer company an extra $322,000 in stamp duty on a house purchase could come back to haunt taxpayers to the tune of billions of dollars as he pursues a damages claim under international trade laws.

Mr Palmer’s private company Mineralogy bought a mansion in the leafy Perth suburb of Applecross in 2019 for $4.6 million. Now, with jurisdiction a key issue, his Singapore-headquartered Zeph Investments is chasing almost $US200 billion ($299 billion) in damages from Australia in a case related to stalled iron ore projects and “emergency legislation” passed by the WA government.