Lagging variables is frequently justified (or even necessary) in empirical legal research. This is particularly so in event-study research that seeks, e.g., to explore the influence of a new law, statute, court decision on various outcome variable(s) of interest. In such contexts researchers need to account for a natural delay in an hypothesized intervention's effect. This topic was raised in a recent Stata blog post (here) that also references relevant Stata coding.
As explained in the comments (slightly edited): "As for the reason behind it [lagging a var], ... this is a scientific, not a statistical issue.... Just generally, it is often the case when longitudinal data is available, that one expects the effects of one variable on another to appear with a delay. That is, this year's value of Y may depend on last year's value of X rather than on the current value. Indeed, it can be more general: sometimes one expects Y to depend on a value of X from several years back, or even jointly on more than one past year. Just when those situations arise depends on the subject matter and the science."