The WA Government has now introduced restrictions on travel to Western Australia (click here for more information). A person will not be in breach of these restrictions if they are required to enter Western Australia under, or to give effect to, an order of an Australian court.
Insofar as travel from WA is concerned, whilst there is no restriction in leaving WA, each other state or territory may have, or may introduce, their own travel restrictions. Parties should make their own enquires in that regard.