"Today, 47 countries in the world, 27 of which are in the Council of Europe, provide some form of legal recognition for same-sex couples," wrote Muižnieks on the CoE website.
"The strongest disagreements seem to crystallise around the notion of 'marriage'," he wrote, pointing out that many CoE member states do not provide any form of legal recognition for same-sex couples.
"Providing access to legal recognition to same-sex couples boils down to a simple concept: equality before the law," Muižnieks wrote.
He also differentiated between civil and religious marriage. "There are arguments in favour of providing access to civil marriage to same-sex couples. One is to ensure that the rights available to same-sex and to different-sex couples are truly equal," he said.
Muižnieks said that gay rights activists in San Marino, Slovakia and Latvia have told him same-sex couples face specific problems, such as lack of inheritance, insurance trouble, not being entitled to a survivor's pension and lack of visitation rights in the hospital.
Two years ago the Saeima turned down Latvian MP Veiko Spolitis' attempt to introduce same sex partnership legislation to the Latvian parliament.
A 2015 proposal that would require MPs to consider allowing same-sex unions is still two thousand short of the 10,000 signatures needed at the public initiative website Manabalss.lv.
To date, Estonia is the only Baltic state to recognize same-sex unions, which it did in 2014.