Sometimes what is called mercy for one person is harm to others. Of course, this is not always the case. The decisions about punishment for crimes that do not (and never can) make the victims whole fall in this category; a life sentence or a death sentence cannot restore the life of a murder victim. These, though, are not all the places where mercy is exercised.
Some people consider it mercy to allow a criminal alien to remain where he or she has chosen to reside, instead of repatriation to his or her home. If this causes harm to others, is this really mercy? By staying here, local wages are depressed. Schools become overcrowded. The number of available jobs is reduced. Roads are more crowded. The housing market has to deal with more residents.
It’s often the people on the margins that are pushed over the edge by these circumstances. Someone with low skills has difficulty getting hired because there are more applications for every job. It takes an extra twelve minutes a day to commute to work, losing an hour in work-life balance each week. The teenager can’t get as many lawns mowed each summer.
Lack of social pressure to conform to healthy behavior can be a false mercy as well. Instead of dwelling on emotional trauma, encouragement to build resilience, though it looks like cruelty, ultimately results in a much greater mercy.
So in showing mercy, do not be unmerciful to others, for a false mercy to one is an injury to another.