Is forging another&#39;s signature prosecutable if forger had permission?
<p>After reading <a href="https://money.stackexchange.com/questions/69158/the-proper-way-a-wife-should-endorse-her-husbands-check">this post</a>, I realized that a significant percentage of my friends and family could go to prison for forgery.  Many couples I know sign one another's names all the time, including on the backs of checks.  My wife and I have given one another blanket permission to sign for one another, and I know many other people with a similar understanding.</p>

<p>In the United States, is it in fact illegal to sign someone else's signature on the back of a check if one has permission to do so?  How about signing my wife's signature on our IRS forms?</p>

<p>Take the laws of Washington to be typical. <a href="http://app.leg.wa.gov/RCW/default.aspx?cite=9A.60.010" rel="nofollow noreferrer">RCW 9A.60.010</a> defines crucial terms:</p>
<blockquote>
<p>To &quot;falsely complete&quot; a written instrument means to transform an
incomplete written instrument into a complete one by adding or
inserting matter, <em>without the authority of anyone entitled to grant
it</em>;</p>
</blockquote>
<p>and:</p>
<blockquote>
<p>&quot;Forged instrument&quot; means a written instrument which has been falsely
made, completed, or altered</p>
</blockquote>
<p><a href="http://app.leg.wa.gov/RCW/default.aspx?cite=9A.60.020" rel="nofollow noreferrer">Forgery</a> then requires a bad intent:</p>
<blockquote>
<p>(1) A person is guilty of forgery if, with intent to injure or defraud:</p>
</blockquote>
<p>where</p>
<blockquote>
<p>(a) He or she <em>falsely makes, completes, or alters</em> a written instrument
or;</p>
<p>(b) He or she possesses, utters, offers, disposes of, or puts off
as true a written instrument which he or she <em>knows to be forged</em>.</p>
</blockquote>
<p>In the scenario described, there is no intent to injure of defraud, and furthermore the document is not forged, because a forged document is one made / completed without authorization.</p>

united-states forgery