What are the _vertical_ limits of a country&#39;s (or other entity&#39;s) territory?
<p>The examples deal with the US, but I'd also be curious about similar laws relating to other countries.</p>
<p>Imagine there is an underground cave or tunnel whose entrance is in Sonora, Mexico, but which extends underground to pass under the territory of Arizona, United States. Now imagine that a woman enters the cave or tunnel and knowingly walks into the part that is under Arizona.</p>
<ul>
<li>Assuming she is not a US citizen, LPR or visa holder, has she illegally entered the country?</li>
<li>If she commits a crime while in that area, would a court in Arizona have jurisdiction to try her for it? What about a court in Sonora?</li>
<li>If she gives birth to a child while in that area, would the child be a US citizen by <em>jus soli</em> ? Would it be a Mexican citizen?</li>
</ul>
<p>Now imagine that instead of an underground passage, any of the events occurs in one of the following situations:</p>
<ul>
<li>She has jumped across the border line, but has not yet landed (okay, hard to imagine a child being born in this short of a time, but surely a crime could be committed while in the air)</li>
<li>She is in an airplane crossing the airspace over Arizona</li>
<li>She is an astronaut on the International Space Station, which happens to pass over Arizona in its orbit.</li>
</ul>
<p>If there is any difference between the &quot;jumping&quot;, &quot;airplane&quot;, and &quot;space station&quot; answers, why? Is there a specific altitude at which territorial jurisdiction expires?</p>

<p><strong>Down</strong> - to the centre of the Earth. In a practical sense, 10km or so.</p>
<p><strong>Up</strong> - to the edge of <a href="https://law.stackexchange.com/questions/70307/where-does-outer-space-legally-start/70309#70309">space</a>.</p>
<blockquote>
<p>Assuming she is not a US citizen, LPR or visa holder, has she illegally entered the country?</p>
</blockquote>
<p>Has she entered the country? Yes.</p>
<p>Is this illegal? Well, presuming it is not a place &quot;designated by immigration officers&quot; for <a href="https://www.law.cornell.edu/uscode/text/8/1325" rel="nofollow noreferrer">entry</a>? Yes, irrespective of any residency or visas she holds. Only US citizens may enter at other than designated crossing places.</p>
<blockquote>
<p>If she commits a crime while in that area, would a court in Arizona have jurisdiction to try her for it?</p>
</blockquote>
<p>Yes.</p>
<blockquote>
<p>What about a court in Sonora?</p>
</blockquote>
<p>Maybe. It depends on if the crime triggers some form of extraterritorial Mexican jurisdiction.</p>
<blockquote>
<p>If she gives birth to a child while in that area, would the child be a US citizen by jus soli ?</p>
</blockquote>
<p>Yes.</p>
<blockquote>
<p>Would it be a Mexican citizen?</p>
</blockquote>
<p>If the mother or father is a Mexican, yes. Also, if the person is born on a Mexican-registered vessel or aircraft which seems unlikely in the circumstances.</p>
<blockquote>
<p>She has jumped across the border line, but has not yet landed (okay, hard to imagine a child being born in this short of a time, but surely a crime could be committed while in the air)</p>
</blockquote>
<p>Same answers apply.</p>
<blockquote>
<p>She is in an airplane crossing the airspace over Arizona</p>
</blockquote>
<p>What is the nationality of the airplane? Is this a commercial or private flight? Is its source or destination in the US, Mexico, both or neither? Has she passed through any nation's immigration?</p>
<blockquote>
<p>She is an astronaut on the International Space Station, which happens to pass over Arizona in its orbit.</p>
</blockquote>
<p>The ISS is subject to it's own <a href="https://law.stackexchange.com/questions/12104/what-happens-if-a-murder-occurs-in-space/12108#12108">treaties</a> - it depends on her nationality and what part of the ISS she is in at the time.</p>

jurisdiction