Two bodies of law govern a private equipment rental in the United States, and they overlap. The first is the common law of bailment, developed state by state, which imposes a duty of ordinary care on the renter and makes them liable for damage caused by negligence or by use outside the agreed scope. A renter who takes a rented pressure washer onto a job the owner never authorised has committed a conversion, and the measure of damages jumps from repair cost to full value of the item. The second is UCC Article 2A, the leasing statute, adopted in every state except Louisiana, which supplies default rules on warranties, risk of loss, remedies, and enforceability.
Article 2A's statute of frauds is where the writing requirement bites. Under §2A-201, a lease is unenforceable unless it is in writing and signed by the party against whom enforcement is sought once total payments, excluding renewal or purchase options, reach $1,000 or more. Below that threshold an oral hire is technically valid, which is precisely why so many neighbour disputes turn into swearing contests over what was agreed. Get it in writing regardless of value.
The consumer overlay matters too. §2A-103(e) defines a consumer lease as one made by a lessor regularly engaged in leasing or selling, to an individual taking the goods primarily for a personal, family, or household purpose. A one-off rental between private parties usually falls outside that definition, which means the consumer protections in §2A-106 on choice of law and forum do not apply, and the parties have wider freedom of contract. Owners who rent out the same items repeatedly should assume the opposite: repeated hiring can make you a lessor "regularly engaged in the business", triggering consumer lease treatment and, in several states, licensing or disclosure obligations. The detailed section text is published by the Cornell Legal Information Institute's annotated text of UCC Article 2A on leases.
One more limit. §2A-503(3) makes any attempt to exclude consequential damages for personal injury in a consumer goods lease prima facie unconscionable. A liability waiver in a rental of a table saw or an ATV will not survive a serious injury claim, whatever the form says.