I'm just writing a paper for history and I've come across a problem. I've been reading through a few books and I can't find an answer to this question. Since "cleric" and "clerk" are derivations from the word clericus, could any cleric or clerk claim the benefit of clergy, even if they weren't ordained?
I'm not comfortable commenting on the whole of medieval Europe, but I can answer the question as far as English law goes.
Simply put, depending on what period you are looking at, any male person could claim benefit of clergy so long as they could read a Latin passage from the Bible.
The background is a bit complex and involves a power struggle between Henry II of England and the church and the murder of Thomas Beckett, but basically it was decided in 1170 that members of the clergy would not be tried in secular courts but in ecclesiastical courts using canon law (no bloodshed allowed in sentencing).^1 Because the ecclesiastical court couldn't hand out the death penalty, claiming benefit of clergy was a really attractive option to laypeople charged with capital crimes.
Initially, the law demanded that a person claiming benefit of clergy had to show up looking the part - they needed to be tonsured and be wearing the appropriate habit or robes (authentica habita - it also applied to university students beginning in the twelfth century). Now I'm not 100% on exactly this change occurred, but literacy was so dismal in this period that only extremely well-educated people and members of the clergy could read Latin. Eventually the rules were relaxed a bit and as long as you were a man and could recite/read Psalm 51 (Miserere mei, Deus, secundum misericordiam tuam) you could presumably claim benefit of clergy. There was no need to look the part or have someone vouch that you really were clergy. If the court chose a different passage and the individual didn't have that one memorised they would likely be exposed.^2
So, to answer your specific question - yes, a clerk who could read Latin (or sound it out at least) could claim benefit of clergy, read the chosen passage and skate off to the ecclesiastical court to receive a non-capital sentence.
Not everyone was successful, but it did get to be a problem for the courts. John G. Bellamy has found that about 13-17 per cent of convictions for clergy-able offences resulted in a successful claim prior to the mid-fourteenth century. In one assize circuit, this percentage grew to 26 per cent between 1399 and 1407.^3 This prompted some revisions and various rulers enacted Benefit of Clergy Acts in 1402 (4 Hen. 4 c.3), 1496 (12 Hen 7 c. 7) and 1575 (18 Eliz. 1 c. 7). These made the crimes of petty treason, murder, rape and burglary "unclergyable offences" which meant no one could claim the benefit. Benefit of clergy was officially taken off the books in the nineteenth century (9 Geo. 4 c.31) (seriously, it was around that long!).
Rosenwein, Barbara H. A Short History of the Middle Ages. Third Edition. Toronto: University of Toronto Press, 2009. p.225-228
Gabel, Leona Christine. Benefit of Clergy in England in the Later Middle Ages (Smith College Studies in History, 14:4). Northampton, MA: 1929 [re-issued in 1964 by Octagon Books in 1969]
Bellamy, John G. The Criminal Trial in Later Medieval England: Felony Before the Courts from Edward I to the Sixteenth Century. Toronto: University of Toronto Press, 1998. p. 136.