The United States Supreme Court is set to conclude its hearings on the constitutionality of same-sex marriage today. On Tuesday the court heard arguments in favor of and against Proposition 8, the California same-sex marriage ban. Today the justices will consider the Defense of Marriage Act (DOMA), which was signed by President Clinton in 1996 and defines marriage as between one man and one woman, denying same-sex couples federal benefits.

From an economic perspective, many favor the idea of marriage equality. If same-sex marriage was legalized, both the wedding and divorce industry could receive a $9.5 billion boost from the nearly 800,000 same-sex couples currently living together. Municipalities would increase revenue because of wedding licensing fees; New York City received a reported $250 million in revenue after lifting their ban on gay marriage. Companies like Tiffany’s (TIF), Marriot (MAR), and Williams-Sonoma (WSM) are just some that would feel the impact of this boom.

But business in general benefits from same-sex marriage, argues John Taft, CEO of RBC Wealth Management-U.S.

“Companies who create an environment where employees are free to be authentically and completely who they are have more engaged employees and that translates into client and customer satisfaction,” says Taft. “I can tell you that if you do not extend benefits to same-sex partnerships, you are not competitive in the business world right now. The bottom line for excluding that population set from your benefit policy is going to be compromised not helped.”

Many business leaders have come out in support of same-sex marriage.

Starbucks (SBUX) CEO Howard Schultz made headlines just this week when a shareholder questioned whether the company’s support of marriage equality was hurting its bottom line. “If you feel, respectfully, that you can get a higher return than the 38% you got last year, it’s a free country,” Shultz replied. “You can sell your shares of Starbucks and buy shares in another company. Thank you very much.”

Lloyd Blankfein, CEO of Goldman Sachs (GS), recorded a commercial supporting marriage equality last year stating. “America's corporations learned long ago that equality is just good business and is the right thing to do,” he said in the ad.

“The economic benefits of same-sex marriage have been recognized by businesses around the country for years,” Taft says. “In many ways the corporate community is ahead of where we are socially because the largest corporations in the United States already recognize partnerships and same-sex marriages in their humans rights and benefits policies.”