Note: landlord laws vary form country to country.
Laws have to be followed by any one. People mostly violate them due to ignorance. But it is not a valid reason that a court will let you go despite the fact that other party has some damage. Landlords also break laws some times and their nature is almost similar in many cases although penalties may differ depending upon the damage. This difference also depends upon the relationship of the tenant and landlord. They usually break law because they are unfamiliar to it. Some of the penalties for breaking landlord laws in different cases are described below.
In many cases gas safety is not ensured and this may become very severe. Usually there is gas leak in a pipe or through any appliance that could be very dangerous. Fine for it is almost 1500$ and also may be prisoner in severe cases.
Gas fire is also in many cases inappropriately settled. He may be fined 1,000$.
Landlord may get a safety certificate from non certified engineer. A plenty of 3000$ is there.
Gas appliances are not checked properly. Fine of 1800$.
And the penalties for breaking landlord laws in maintaining sector causing health and other problems may result in the shape of huge fine starting from 5,000$ up to 9,000$ depending upon conditions.
Some times landlord may evict his tenants illegally with force, he may be charged up to 10,000$ fine.
Landlord has to repair his property regularly and some time especially when needed to bring his property up to minimum required safety level. And if he is failed to do so, he may have a plenty of approximate 4,000$ to 5,000$ and it is 100 times the annual repairing cost of property.
Different types of the penalties for breaking landlord laws concerning license are also there. For example if he has not a license of multiple occupancy, he may suffer up to 2000$ fine.
And the most important is to declare his annual income; reversibly he may be jailed for 1 to 2 years.