Ok, in Maryland the husband is presumed to be the child's father. This is a very strong presumption. The other man would have to file a paternity suit and try to convince a court to order paternity testing if he can prove it would be in the child's best interest. (Stubbs v. Colandrea
, 154 Md. App. 673, 841 A.2d 361 (2003)). However, I would opine that is unlikely to happen, in my estimation, if your husband has been taking the role of father and wishes to continue in that role.
The courts are hesitant to disturb a family relationship unless there is compelling evidence for them to do so. In a recent case, Mulligan v. Corbett, the same situation arose and the circuit court
judge denied the petition under the Estates and Trusts article that gives a judge discretion whether to allow testing. The man claiming paternity appealed up to the Supreme Court and they upheld the circuit court's ruling after explaining that a paternity case is presumably to establish legitimacy and that a self-proclaimed father seeking DNA testing would have to show that the testing was in the child's best interests.
Relying on the Estates and Trusts article that gave him discretion as to whether to allow testing, the circuit court denied the Respondent’s request for paternity testing. - See more at: http://www.marylanddivorcelawyer-blog.com/2013/07/16/when-can-a-maryland-man-ask-the-court-for-genetic-paternity-testing/#sthash.okFTi0JO.dpu
They then reasoned that since the child was conceived during the marriage, the husband was the legal father and refused to order a DNA test.
But to answer your question directly, yes, the other man could file a paternity lawsuit and try to get a judge to order a DNA test, but I would opine that a judge would deny the peitition.