Even 40 - 50% quoted by that author is a clear over representation of this religion/culture/grouping in France Prison populace.
Is Muslim incarceration rates a problem in Europe? Yes and no.
Let me put things in perspective a bit..
The incarceration rates in Europe are
extremely low compared to United States or rest of the world. Let's take a look at the situation between black incarceration in the United States vs the Muslim incarceration in Europe.
Around
850,000 African Americans are in jail in the United States alone. As for Muslims, there are less than 80,000 Muslims in jails across Europe! And remember, there are
millions of more Muslims in Europe than blacks in America.
So as a whole, the issue is not that big. There are approximately 50 million Muslims in European mainland. 80,000 or so Muslim prisoners out of a population of
40 to 50 million? Pretty satisfactory numbers.
However, it is true that Muslims are disproportionally present in European prisons compared to their numbers in the general population. Why is that? Well there are many reasons..
Class differences:
Muslims in countries like France and Germany etc are like Hispanics in America. That is, they mostly belong to the working/labor class families since most of them hail from the low-wage workers that migrated to Europe to fil up the low-wage workers' demand there (just like Hispanics came to the U.S in huge numbers as low-wage workers).
It is a well-known fact that people from lower socio-economic classes tend to do more crimes. And since Muslims are disproportionally represented in lower socio-economic classes in Europe--it's no surprise that Muslims are more likely to be in prison than the general population.
Discrimination:
Just like Blacks in America, Muslims in Europe face discriminatory behavior from the law enforcement and justice systems in Europe. It is kind of a self-fulfilling prophecy situation. Law enforcement focus more on a certain group (Muslims in Europe, blacks in the US) and end up finding more crime within that group (due to their extra focus)...and thereby consolidating the view that certain groups should be given more focus because of higher crimes from them. And the cycle goes on. In America, blacks and whites use marijuana at similar rates--but blacks are more than four times more likely to get caught for illegal marijuana possession. Why? Well because of the increased focus from the law-enforcement.
Conversion:
I am sure you know about the prison Islam phenomenon? A lot of prisoners (in thousands) have ended up converting to Islam in the prison system throughout the Western world. A lot of factors go into it. More discipline, sense of brotherhood and belonging, more protection in cases where Muslim gangs are stronger in prisons, and so on. So the actual number of 'Muslim prisoners in prison' get inflated by this phenomenon. Say 200 Muslim prisoners are caught from street and put in a jail. And say 75 non-Muslim prisoners end up converting to Islam. For an outside researcher, the total number of Muslims in prison would be 275---but that is not to say that 275 Muslims were caught from street for crimes. So you see how the numbers of Muslims in prison end up getting inflated and don't entirely present the true situation
These are few points regarding the issue. There are many other factors as well. Hopefully it helps..
@Vergennes