Private landlords have complained that there will be 168 pieces of legislation governing their relations with tenants once the new Building Safety Bill passes through Parliament.
The National Residential Landlords Association (NRLA) said some dated back to the 18th century, such as the Landlord and Tenant Act 1730.
It said this large volume of laws meant it was impossible for local authorities to effectively enforce all of them.
In 2017-18, it found 89% of local authorities issued no civil penalties against private landlords and more than half had no civil penalty policy in place.
The Government has said it will introduce a White Paper on the private rented sector in the autumn, but the NRLA said there should first be a full assessment of the ability of councils to enforce the powers already available.
Any proposals to improve the sector for tenants and responsible landlords would be undermined if regulations cannot be enforced properly, and would serve only to help those providing sub-standard accommodation, the NRLA said.
It also said the Law Commission should review current laws to assess whether they are fit for purpose, and propose updated and potentially consolidated legislation.
NRLA chief executive Ben Beadle said: “The laws underpinning the private rented sector are not fit for purpose. They are failing to protect responsible landlords and tenants from the actions of those who bring the sector into disrepute.”
The NRLA has issued a report, titled Not Under-Regulated But Underenforced: the legislation affecting private landlords in England.
Under the Building Safety Bill, a Building Safety Regulator will become responsible for ensuring that any building safety risks in new and existing residential buildings of 18m and above are managed and resolved,
Communities Secretary Robert Jenrick said the reforms would tackle the bad practice identified in Dame Judith Hackitt’s 2018 review of Building Regulations and fire safety, following the Grenfell Tower blaze.
The period in which residents can seek compensation for substandard construction work will increase from six to 15 years, and this will apply retrospectively to 2010.