Historically in the United States, families fit into a traditional mold: women were stay-at-home wives who raised the children, and men were the breadwinners who spent little time with them.
But that mold has been changing over the past few decades. Fathers have been increasingly involved in their kids’ lives and there are a few likely reasons for this change. As the number of women in the workforce increased, the number of stay-at-home dads increased as well. In 2012, 1 in 6 U.S. fathers were stay-at-home dads. Changes in some state policies have provided paternity leave and adoption leave for fathers so they had the opportunity to bond with their children. In fact, in the US nine out of ten fathers take some time off work when a new child comes into their family. Scientists are just beginning to realize the effects this has on children. Studies have found that a father’s involvement has a positive effect on a child’s intellectual and emotional development. And fathers’ increased involvement has naturally affected how courts determine parental responsibility.
While families come in all shapes and sizes, many people believe that there is a tendency for a court to favor the mother in a custody determination for a traditional, nuclear family. However, this is not true. Colorado law explicitly prohibits a court from presuming a party will better serve a child’s best interest because of their sex.
In addition, Colorado law emphasizes that parents should share parenting, if it is in the best interest of the child. It explicitly states, “the general assembly urges parents to share the rights and responsibilities of child-rearing and to encourage the love, affection, and contract between the children and the parents.” 
In determining the best interests of the child, courts look to factors set out by the law including the wishes of the parents, the wishes of the child, the interaction and interrelationship with the child and his or her parents, and others. Colorado courts have fully embraced the idea that time with both parents is in the best interest of the child in the majority (?) cases. This standard extends to same-sex couples who are parents as well.
In June 2015, the US Supreme Court ruled that the right to marry was a fundamental right that extended to same-sex couples in a case known as Obergefell v. Hodges. Before this, same-sex couples could either marry in Colorado (as of October 2014) or enter into a civil union (as of May 2013) in the state. But the Supreme Court’s decision in Obergefell paved the way for same-sex couples to legally marry and adopt. Since then, Colorado has seen an uptick in custody litigation in same-sex couples.
However, a recent Colorado Supreme Court ruling may lead to a surge in custody cases for same-sex marriages that were entered into under common law. Colorado is one of the few states that recognizes common law marriages. These are marriages that are entered into based on the couple’s conduct. In the beginning of 2021, the Colorado Supreme Court determined that Obergefell’s prohibitions on same-sex marriage was retroactive and applied to common law marriages. Since Colorado started recognizing common law marriages in the 1880s, many same-sex couples may have entered into valid common law marriages before 2014. Any future divorces between these couples may lead to child custody litigation.
The increased residential mobility of people has led to a growing number of both removal and international custody cases. But these cases are not without their barriers. When one parent attempts to relocate with the child, the relocating parent must show that the relocation is in the best interest of the child. This is a hard burden to prove, as Colorado courts emphasize shared parental rights responsibility.
For the most part, removal cases are based on one parent attempting to relocate to another state. Studies have repeatedly shown that divorce can spur residential mobility, and often to far away states. One 40-year study from 2002 found that the average distance between divorced parents’ residences was 400 miles. With the recent increase in residential mobility that has occurred since 2002, this number may even be higher now.
International custody cases have also been on the rise as more Americans move abroad. There may be some recourses for parents whose children have been or may be abducted and moved internationally. Colorado has adopted both the international Hague Convention, as well as the Uniform Child Abduction Prevention Act. However, international custody cases are generally difficult to litigate because of jurisdictional and international law issues. International custody agreements and visitation schedules between collaborative parents are highly encouraged.
Family law practices have recently seen an increase in custody litigation between unmarried couples. These cases may be based on Allocation of Parental Responsibility, or determination of the paternity of the child.