__It is not possible to state a general principle which accounts for the diversity of situations in which an equitable lien arises. __Hewett v Court (1983) 149 CLR 639 at 645, Aust HC, per Gibbs CJ.
Apart from equitable liens arising from contractual dealings in property, equitable liens have been based upon general considerations of justice or upon the principle that he who seeks the aid of equity in enforcing some claim must admit the equitable rights of others associated with the subject matter. Shirlaw v Taylor (1991) 102 ALR 551 at 557-558, Aust Fed Ct, Full Ct.
The vendor’s lien is founded on the principle of equity that he who has obtained possession of property under a contract for payment of its value will not be allowed to keep it without payment. Where through the deposit of deeds and compliance with the statutory formalities, an equitable mortgage arises, there is a lien on the documents.
705. Concurrent Legal and Equitable Liens. Legal and equitable liens may both arise in the same transaction. Thus on the sale of land the vendor’s or purchaser’s equitable lien exists concurrently with a more limited legal lien before conveyance and a legal lien on the title deeds in the claimant’s possession; and it would also seem that a legal lien arising by statute on the sale of goods may exist concurrently with an equitable lien on the same goods. An equitable charge over a chattel can co-exist with a bailment of the chattel: Re Cosslett (Contractors) Ltd [1996] 4 All ER 46 at 61, [1996] 3 WLR 299 at 314 per Jonathan Parker J.
706. Statutory Lien. Where a lien arises by virtue of statute there will be different considerations from those raised by a common law or equitable lien, because the primary question will be the meaning of the statute; and it will not necessarily follow that the principles affecting a common law or equitable lien are intended by the statute to apply.
Statute law may also destroy or nullify a lien which would otherwise be enforcable. An accountant’s lien in respect of unpaid fees over a client’s books of accounts, files and papers is unenforcable in so far as the existence of the lien conflicts with the requirement imposed by the Companies Act 1985 s 222 (as substituted) […] that a company’s accounting records must be kept at the company’s registered office or such other place as the director’s think fit, and must at all times be open to inspection by the company’s officers: DTC (CNC) Ltd v Gary Sargeant & Co (a firm) 2 All ER 369, [1996] 1 WLR 797.
It may not be clear whether the statute creates a general or a particular lien. __See eg Consumer Credit Act 1974 ss 70(2), 73(5); cf s 72(4). __An example of a statutory particular lien is that created in favour of the unpaid seller by the Sale of Goods Act 1979 [ss 39, 42, 43, 47, 48, 55].
707. Contractual Lien. Where a lien arises by contract there will usually be different considerations from those raised by a common law or equitable lien, because the primary question will be the meaning of the terms of the contract.
Contract has been said to supersede lien and to limit the rights of the person claiming under contract to those for which provision has been made in the contract. Walker v Birch (1795) 6 Term Rep 258; Re Leith’s Estate, Chambers v Davidson (1866) LR 1 PC 296; Fisher v Smith (1878) 4 App Cas 1, HL; Seka Pty Ltd (in provisional liquidation) v Fabric Dyeworks (Aust) Ltd (1991) 4 ACSR 455, Aust Fed Ct. An example of a contractual lien is a security within the terms of the Consumer Credit Act 1974.
A contract which puports to create a general lien will be strictly construed. Squamish Terminals Ltd v Price-Waterhouse Ltd (1980).
Just as a contract may supersede the lien, so a course of dealing inconsistent with the lien may destroy it. Fisher v Smith (1878 4 App Cas 1, HL.