united-states
What prevents laws from being interpreted pedantically?
<p>In <a href="https://ham.stackexchange.com/questions/16268/do-fcc-obscenity-regulations-apply-to-ham-radio-transmissions/16271?noredirect=1#comment25138_16271">some discussion on another StackExchange</a>, <a href="https://www.law.cornell.edu/uscode/text/18/1464" rel="noreferrer">18 US Code §1464</a> came up, which states:</p>

<blockquote>
  <p>Whoever utters any obscene, indecent, or profane language by means of radio communication shall be fined under this title or imprisoned not more than two years, or both.</p>
</blockquote>

<p>Interpreted literally, this is quite absurd: it would mean one can't curse on a cell phone, or view (otherwise legal) pornography with WiFi, both of which I'm pretty sure are legal activities within the US.</p>

<p>I'm not so much worried this particular issue, but I am curious about the general case: there must be thousands of things like this which can be interpreted literally to make a subjectively absurd argument. What is the general principle that keeps application of law sane, and not devolve into chaos and pedantry?</p>

<p>This ultimately is a matter of <a href="https://en.wikipedia.org/wiki/Statutory_interpretation" rel="noreferrer">Statutory Interpretation</a>. One of the principles of statutory interpretation is that all words are interpreted in their context. For your example, that means we look at the title of 1464, "Broadcasting obscene language". From this it becomes apparent that radio is used in its common meaning of AM and FM radio broadcasts.</p>

<p>Statutory interpretation is broader than that single rule, though. Legislative intent is another important factor, and that is rather effective in eliminating absurd arguments. Via the link above, from New Mexico's State Court: words have their ordinary meaning <em>"as long as the ordinary meaning does not render the statute's application absurd, unreasonable, or unjust."</em> In other words, absurdity is so bad that the court will prefer an alternative interpretation of the offending words.</p>

<p>To supplement MSalters' answer, <a href="https://www.law.cornell.edu/uscode/text/18/1464" rel="noreferrer">18 USC 1464</a> results from a large-scale reorganization of federal criminal law in 1948. It comes from the <a href="https://transition.fcc.gov/Bureaus/OSEC/library/legislative_histories/47.pdf" rel="noreferrer">Communications Act of 1933</a>, which (§ 326) states that "No person within the jurisdiction of the United States shall utter any obscene, indecent, or profane language by means of radio communication". . Radio communication is defined in that act: </p>

<blockquote>
  <p>means the transmission by radio of writing, signs, signals, pictures,
  and sounds of all kinds, including all instrumentalities, facilities,
  apparatus, and services (among other things, the receipt, forwarding,
  and delivery of communications) incidental to such transmission</p>
</blockquote>

<p>and is distinct from wire or telephone commnuication. "Radio" is not defined. In interpreting this law, the courts can (probably would, if one side made the argument) consider "legislative intent" in determining what this piece of verbiage means. In historical context, it refers to broadcast radio, and not <em>all</em> forms of electromagnetic transmission such as have come into existence since the law was passed.</p>

<p>Common sense, <a href="https://en.wikipedia.org/wiki/Selective_enforcement" rel="noreferrer">prosecutorial discretion</a> and <a href="https://en.wikipedia.org/wiki/Jury_nullification" rel="noreferrer">jury nullification</a>.</p>

<p>Laws are applied by people, not computers. Those people are mostly reasonable — they tend not to apply laws where such application will cause chaos. Where this becomes less feasible, the laws get eventually changed.</p>

<h2>Law and politics</h2>
<p>Courts interpret the law in the context of particular cases. These courts are themselves an integral part of the law they interpret and how they interpret the law is part is the law itself. This goes by the name of <a href="https://en.wikipedia.org/wiki/Judicial_interpretation" rel="noreferrer">Judicial interpretation</a> or, more narrowly, <a href="https://en.wikipedia.org/wiki/Statutory_interpretation" rel="noreferrer">Statutory interpretation</a>.</p>
<p>There a multitude of different techniques for doing so; including the <a href="https://en.wikipedia.org/wiki/Plain_meaning_rule" rel="noreferrer">plain meaning rule</a> (or <a href="https://en.wikipedia.org/wiki/Strict_constructionism" rel="noreferrer">strict constructionism</a> as its called when applied to the US constitution) that your question is concerned with. This rule was explained in <a href="https://swarb.co.uk/the-sussex-peerage-case-1844/" rel="noreferrer"><em>The Sussex Peerage Case</em> (1844; 11 Cl&amp;Fin 85)</a>:</p>
<blockquote>
<p>Acts should be construed according to the intent of Parliament. If the words are clear no more can be done than to use their natural meaning. The words alone do declare the intention of the lawgiver.</p>
<p>...</p>
<p>If the words of the statute are in themselves precise and unambiguous, then no more can be necessary than to expound those words in their natural and ordinary sense. The words themselves alone do, in such case, best declare the intention of the lawgiver.</p>
</blockquote>
<p>The limitations of this were illustrated in <a href="http://www.e-lawresources.co.uk/Whitely-v-Chappel.php" rel="noreferrer"><em>Whiteley v. Chappel</em> (1868; LR 4 QB 147)</a>. A statute made it an offence 'to impersonate any person entitled to vote.' The defendant used the vote of a dead man. The statute relating to voting rights required a person to be living in order to be entitled to vote. The defendant was therefore acquitted.</p>
<p>The advantages of the literal rule are that it:</p>
<ul>
<li><p>Restricts the role of the judge</p>
</li>
<li><p>Provides no scope for judges to use their own opinions or prejudices</p>
</li>
<li><p>Upholds the separation of powers</p>
</li>
<li><p>Recognises Parliament as the supreme law maker</p>
</li>
</ul>
<p>The disadvantages are that it:</p>
<ul>
<li><p>Can lead to injustice (see <a href="http://www.e-lawresources.co.uk/London-and-North-Eastern-Railway-v-Berriman.php" rel="noreferrer"><em>London and North Eastern Railway v Berriman</em> [1946] AC 278</a>,</p>
</li>
<li><p>creates weird precedents which only a higher court or parliament can correct,</p>
</li>
<li><p>(wrongly) assumes that written English is plain, unambiguous and immutable in meaning over time,</p>
</li>
<li><p>it does little to dissuade the opinion of the public that <a href="https://www.goodreads.com/quotes/22816-it-was-all-mrs-bumble-she-would-do-it-urged" rel="noreferrer">the law is a ass</a> as Dicken's Mr Bumble observed when told that the law supposed that he directed the activities of his wife.</p>
</li>
</ul>
<p>Nevertheless, this is still the first port of call for a judge - assume the law says what it means and means what it says. Only if that leads you into absurdity, injustice, contradiction or thwarting the stated intent of parliament do you apply other rules of construction.</p>
<p>However, the law is self-correcting (to an extent) and a litigant unhappy with a judge's interpretation of the law can appeal and get other judges to decide if the first judge was correct or not. Failing that, faced with a string of cases with absurd or perverse outcomes, parliament can change the law; indeed, I have read more than one judgement (usually of appellate courts) where the judge(s) have explicitly called on parliament to do so.</p>

<p>The USA is a country with a common law legal system. This means that previous cases are considered for new cases, and are actually definitive for them; they become part of the law. If a new case matches the details of an old case then the same judgements must be followed. Judgements that differ can be appealed and will often be overruled if they did not follow precedent. It is quite rare for precedent to be changed, and that will usually require the judgement of a quite high court.</p>

<p>So in addition to considering the intent of the authors of this section of the code, and the historical and technical contexts it was written in, lawyers will also look at the previous cases that have interpreted this section of the code because those cases supplement the code and must be followed.</p>

<p>In addition to the interpretive issues raised in other answers, there are also practical, logistical reasons. There simply aren't enough investigators and prosecutors to enforce laws like this too broadly.</p>

<p>So the emphasis is given to the clear, major violators, as prosecuting them will provide the most "bang for the buck".</p>

<p>This does open the door to biased, selective enforcement. If a prosecutor had it out for you, they might decide to look for a law that you've technically violated, even though it would not normally be enforced against you. But they'd still have to get the court to agree to hear the case.</p>
