Not sure about the laws in Europe, but in the USA it is illegal to possess explosives, so landmines would be a quick way to get into prison here. Even companies that have permits to have explosives would not use them to intentionally hurt anyone.
"Explosives" would be a VERY broad definition, something like a bullet is essentially an explosive as well, and one built with the intent of killing someone at that.
One problem is that legislation is often not overly clear on what -exactly- is forbidden, and under (at least most european countries laws) anything that is not defined as illegal is perfectly fine to do.
Unlike the US we have strict gun control here, and owning a firearm is forbidden unless you have a permit to that. But the law defines what a firearm is, which is more or less a 'device that shoots ammunition powered by a chemical reaction' - as far as i can translate it.
That would effectively mean that it would not be illegal for a citizen to have something like a nuclear bomb, fully fuelled saturn 5 missile to fly to the moon, anti-aircraft missile or landmine since they strictly do not fall under such definitions.
There is obviously more generic legislation that would cover things like reckless endangerment regardless of means, or zoning laws that ban storage of large amounts of cryogenic fuels and/or oxidizers preventing you from even having that saturn 5 set up ready to depart.
Actually launching that saturn 5 would be illegal, but the again we don't exactly have cops with missiles capable to follow you to the moon to write a ticket