On October 2008 Mexico’s capital, the Federal District, approved a version of no-fault divorce locally known as “express divorce”. With the new law the requesting spouse no longer had to provide a cause to dissolve the marriage and the couple no longer had to live apart before filing for divorce. Furthermore, the process of determining child custody and alimony were now separate from the divorce trial. The Federal District has so far been the only federative entity in Mexico to adopt a less adversarial divorce system.

A quick look at the monthly divorce data in the Federal District shows that there is a strong seasonal component to divorce with a fall in the number filings during July, December and to a lesser extend January. But more importantly, it shows a big increase in divorces for the year after the law went into effect. The number of divorces filed went from 6,897 in 2007 to 7,410 in 2008, and 9,835 in 2009 (because it takes time to enter the divorces in the vital statistics database the number of divorces are under-counted by about 1% in 2008 and 5% in 2009)
Fitting an ARIMA(1,0,0)(1,0,0)₁₂ model to the divorce data with the strucchange package I find a structural change that coincides with the October implementation of express divorce.
Looking at the divorces that were filed in the Federal District (Distrito Federal) by the state where the marriage took place reveals there’s a very strange pattern whereby the whole increase in the number of divorces can be accounted by people from outside the Federal District taking advantage of its laws to get a divorce. In fact, among people who got married in the Federal District and filed for divorce in the Federal District there was a decrease in the number of divorces!

Notice the y axes of the plot are on different scales

The Federal District was the only entity where there was a decrease in the number of divorces filed:

There were less divorces in the Federal District in 2009 than in 2008

In Did Unilateral Divorce Raise Divorce Rates? A Reconciliation
and New Results Justin Wolfers argues that immediately after the United States adopted no fault divorce there was a big increase in divorces, but the trend reversed after about a decade, that is, the rise in divorces after no fault divorce was adopted was not persistent and the temporary rise may have been due to a backlog of couples who were in bad marriage but had postponed going through a burdensome divorce process.

Since I only have express divorce data for about a year I thought that one way to test if the rise in divorces was on path to becoming permanent would be to look at the trend in length of marriages among those who file for divorce, though of course, it is foolhardy to extrapolate from only one year of data since as more people become aware of the divorce law, they may take it into account in deciding whether and at what age to marry. Or maybe with the introduction of the new law divorce will become more socially acceptable and less stigmatized.

Here’s a table with the total number of divorces (instead of the percentage change) in the Federal District, by length of marriage:

Year	0-1 years	2-4 years	5-9 years	10-14 years	15 or more years
2007	278	1,382	1,844	1,105	2,258
2008	339	1,453	1,852	1,205	2,561
2009	342	1,716	2,358	1,659	3,760

The biggest increase in people filing for divorce was among those who had been married the longest, but remember the previous chart? If we divide the data into those who married in the Federal District and outside it, we come to a completely different conclusion.

Outside the Federal District

Among those who married outside the Federal District we see an increase in divorces among recent marriages

The biggest percentage change outside the DF occurred among those couples who still remember their honeymoons

Here’s a table with the total number of divorces (instead of the percentage change) in the Federal District of marriages that took place outside the Federal District, by length of marriage:

	0-1 years	2-4 years	5-9 years	10-14 years	15 or more years
2007	17	85	194	134	259
2008	23	91	205	144	320
2009	208	877	948	486	1,224

Federal District


Here’s a table with the total number of divorces (instead of the percentage change) in the Federal District of marriages that took place in the Federal Distric, by length of marriage:

	0-1 years	2-4 years	5-9 years	10-14 years	15 or more years
2007	261	1,297	1,650	971	1,999
2008	316	1,362	1,647	1,061	2,241
2009	134	839	1,410	1,173	2,536

In the vital statistics database most of people who filed for divorce in the Federal District but got married outside of it are coded as having lived in the Federal District at the time they filed for divorced. I’m guessing this is probably just a quirk of the law that makes it easy to use a Federal District address and that there really is a lot of “divorce tourism” going on rather than the unique stress of living among chilangos (the inhabitants of the Federal District) causing men and women from provincia (the region of Mexico outside the Federal District) to get divorced.

The proportion of marriages ending in divorce decreased in the Federal District and increased in Morelos and Hidalgo. I have no idea what sort of witchcraft Querétaro uses to ward off the perverting influence of that hotbed of depravity and den sin better known as the Federal District.

One clue lies in the fact that marriages fell in the Federal District a few months before the divorce law went into effect. In 2007 there were 41,427 marriages, in 2008 33,968, and in 2009 32,083. There are various reasons these could have happened

1. An error in the database. But according to this story in Excelsior (link in Spanish) the authorities double checked the data to make sure there were no errors.
2. The story also mentions a price increase but discards that theory as not very likely. A quick internet search reveals the fact that a marriage license costs about $70 US dollars ($900 pesos). Marriage would have to have quite a large price elasticity to fall that much.
3. Another hypothesis is that since abortion was legalized in April of 2007 perhaps pregnancies that previously resulted in shotgun marriages now end in abortions. And it was precisely these marriages that were more likely to end in divorce. When looking at the age specific marriage totals, the younger the bride the bigger the percentage decrease in marriages compared to previous years. But this theory doesn’t explain the fall in divorces among those marriages more than a few years old.

Basically I don’t have an all-encompassing theory of why marriage fell.


P.S. You can download the code from my GitHub account

References

Wolfers, Justin, Did Unilateral Divorce Laws Raise Divorce Rates? A Reconciliation and New Results (August 2003). Stanford Law and Economics Olin Working Paper No. 264; Stanford Law School, Public Law Working Paper No. 68. Available at SSRN: http://ssrn.com/abstract=444620 or http://dx.doi.org/10.2139/ssrn.444620