P is a homosexual man. He has been in a monogamous relationship with his male partner since 2000. P is not medically infertile. But P characterizes himself as 'effectively' infertile because he is homosexual and because it is physiologically impossible for two men to conceive a child through sexual relations. In 2010, P and his partner decided to try to have children through IVF, with Mr. Morrissey serving as the biological father. Between 2010 and 2014, P paid expenses related to (among other things) seven IVF procedures, three egg donors, three surrogates, and two fertility specialists. The IVF process cost P more than $100,000. In 2011 alone-the tax year at issue-P paid nearly $57,000 out of pocket for IVF-related expenses. About $1,500 went toward procedures performed directly on P's body-namely, blood tests and sperm collection. The remaining $55,000 was spent to identify and retain the women who served as the egg donor and the gestational surrogate, to compensate those women for their services, to reimburse their travel and other expenses, and to provide medical care for them. P timely filed an amended 2011 return that claimed a medical expenses deduction in the amount of $36,538. In 2011, I.R.C. § 213 allowed a taxpayer to claim a deduction for 'medical care' expenses that exceeded 7.5% of his adjusted gross income. The $1,500 spent for P's blood work and sperm collection doesn't meet the 7.5% threshold. P can't deduct those expenses unless he can also deduct the much more significant costs associated with the identification, retention, compensation, and care of the egg donor and the gestational surrogate. D denied the deduction. P filed this refund suit asserting two claims. P claims Section 213 authorizes his requested deduction. P also contends that D's disallowance violates the equal protection component of the Fifth Amendment. The district court granted summary judgment for D. P appealed.