It’s a complicated balancing act between the comfort of an apartment tenant who has dog allergies and another tenant who needs an emotional support dog.

In a recent case, the Iowa Supreme Court decided that a building in Iowa City, Iowa, that typically doesn’t allow pets should not have allowed a new tenant to have an emotional support dog when an existing tenant with severe allergies protested.

The allergic tenant sued the landlord for breaching the no-pet provision in her lease and for interfering with her “quiet enjoyment” of her property.

The court held that it was unfair for the landlord to allow the new tenant’s emotional support dog because the allergic tenant was there first and her allergies were clearly noted in her medical records. The new tenant had made the request a month after moving in.

However, the court said the right decision in a given situation depends on the facts. That means a service animal for someone with a visual disability might have trumped an allergic tenant.

The landlord in this case had tried to accommodate both tenants by having them use two separate stairwells and installing an air purifier in the allergic tenant’s apartment. But the attempted solution didn’t work.

The Iowa court noted that other courts have ruled similarly in recent years.

For example, in 2019 a federal appeals court rejected one tenant’s request to ban smoking in her condo complex because she had asthma. The court said that changing to a no-smoking policy would be unfair to third parties.

And in 2018, a federal trial court in Virginia said that an employer who banned an emotional support dog due to another worker’s allergies hadn’t engaged in disability discrimination.