Child custody has changed since the days of Ozzie and Harriet and Leave it to Beaver. The '50s ideal of a stay-at-home wife with a husband who was the breadwinner are long gone. Sometimes the law, in the form of the legislature and the courts, are slow to adapt to these changes.
In Minnesota, there have been amendments to the family law statutes that have changed some of the elements used to decide child custody. While the state has not adopted a presumption of shared custody, the likelihood of a father obtaining shared custody and in some cases, perhaps even primary custody, is much greater today than ever before.
There are 12 factors a judge must consider when determining "the best interests of the child" and there are an additional 9 factors that govern the application of the best interest factors.
The court is not permitted to simply provide a conclusory result. The legislature has instructed it to "make detailed findings on each of the factors in paragraph (a) based on the evidence presented and explain how each factor led to its conclusions and to the determination of custody and parenting time. The court may not use one factor to the exclusion of all others, and the court shall consider that the factors may be interrelated."
You can help the court by providing detailed, factual evidence that supports the conclusions you are arguing. Of course, the ideal situation occurs when the parents can work together to develop a parenting plan without conflict or the need for the court to rule in favor of either side.
A cooperative plan has the advantage of ensuring each parent is "on board" with the plan and willing to work towards its success and the success of their children.