Maybe you’re a LARPer or a fan of Renaissance Fairs. Maybe you’re an engineering or history student, studying the effectiveness of various siege weapons. Or maybe you’ve got a neighbor with high walls and a penchant for playing their music too loud.

Either way, if you’re looking to launch a projectile a great distance (without the aid of explosives), you might be wondering if you can build your own catapult, trebuchet, or similar siege engine without interference from the fuzz. Here’s what you need to know.

Construction Plans

The short, non-answer is of course you can build your own catapult. You can find the plans for one right here on Popular Science, or Scientific American if you prefer. Constructing a small catapult for use in your kitchen or back yard appears to be pretty simple. And there are no laws prohibiting the construction of catapults.

But whether you should build your own catapult, or whether the use of your catapult will be legal, is a bit more complicated. What you do on your own property is generally not the law’s business. (Unless you’re violating particular zoning laws, local ordinances, or homeowners’ agreements.) But that the thing about the average siege engine — they look pretty cool and they don’t keep projectiles nearby. So you may be opening yourself up to civil liability in two ways.

Attractive Nuisance

While you can mostly do want you want on your own land, as a property owner you do have a legal duty to prevent injuries on your property. This responsibility can even extend to trespassers and especially children who might be irresistibly drawn to dangerous objects on your property. The classic example of an attractive nuisance — as they are referred to legally — is a swimming pool, and the law places a special responsibility on pool owners to take steps to prevent kids from entering the property or pool area. Machinery and pumps have been considered attractive nuisances, so it’s likely a trebuchet or catapult would be as well.

Simple Negligence

And should one of your ballistic projectiles find their way onto someone else’s land, you could be liable for any property damage or personal injury that occurs.

Building a catapult or trebuchet can be a fun, educational experience. Just think twice about what you’re launching and where.

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