Audibitis (Audite) me, O Iuris Consulti!(.)

HEAR (Hear) me, O Lawyers!(.)

Today I turn to the trusty mailbag. This, gathering dust sadly, from an AVID reader. Colette writes:

[T]oday in one of my classes we brought up this phrase: subpoena duces tecum, which they translate as "bring with you under penalty of punishment." [I] know i haven't taken Latin for awhile, but something about this just seems wrong to me. Why duces? duco is 3rd, so this looks future in form to me, but it doesn't seem to have any kind of future meaning. [I]t could be a jussive subjunctive, but that would be ducas (plus it would seem not very common to use the second person singular in this kind of construction?). There is a small note I just found in my grammar about futures being used with imperative force, so I guess this must be the explanation, but this is not something I remember seeing before.

Indeed, Colette. It is an easy to miss side note and an unsatisfactory explanation, but here is what Allen and Greenough have to say in their New Latin Grammar:

449. b. The Future Indicative is sometimes used for the imperative.

Seriously?! That's it? That's a pretty lame effort.

Only slightly better is what is found in J.P. Postgate and C.A. Vince's New Latin Primer:

Commands and Requests

In positive Requests besides (1) the Imperative and (2) the Subjunctive of Desire, Latin writers also use forms which are properly Statements, viz. (3) the Future Indicative, which puts the Request as something which will happen, and is thus a strong Command, as hôc faciês you will do this.

I think that we're on the right track, but that it's also a long road. My hypothesis is that the regularity of the future indicative as a substitute for the imperative in modern legal Latin is the result of evolution through Vulgar Latin (sermo vulgaris) and/or Medieval Latin, late bastardizations of the Classical Latin taught in schools. In the Vulgate Bible, a work of direct translation from the original Hebrew, we see St. Jerome render a particularly famous series of commandments with the future indicative, the...um...Ten.

From LatinVulgate:

1. Thou shalt not have strange gods before me.
   non habebis deos alienos coram me

2. Thou shalt not make to thyself a graven thing..
   non facies tibi sculptile ..

3. Thou shalt not adore them, nor serve them...
   non adorabis ea neque coles...

4. Thou shalt not take the name of the Lord thy God in vain...
   non adsumes nomen Domini Dei tui in vanum...

5. Thou shalt not kill.
   non occides.

6. Thou shalt not commit adultery.
   non moechaberis.

...I think that's enough. You get the point. Scholars and the clergy, the only ones still Latin-literate during the later periods, were quite a mixed up bunch. I'm fairly sure that modern legal Latin emerged from the confusion, and retained what had become a common convention.