As states sent Union regiments south, on April 19 Baltimore mobs in control of the rail links attacked Union troops who were changing trains. Local leaders' groups later burned critical rail bridges to the capital and the Army responded by arresting local Maryland officials. Lincoln suspended the writ of habeas corpus in an effort to protect the troops trying to reach Washington. John Merryman, one Maryland official hindering the U.S. troop movements, petitioned Supreme Court Chief Justice Roger B. Taney to issue a writ of habeas corpus. In June, in Ex parte Merryman, Taney, not ruling on behalf of the Supreme Court,"One significant point of disagreement among historians and political scientists is whether Roger Taney heard Ex parte Merryman as a U.S. circuit judge or as a Supreme Court justice in chambers." White, Jonathan W., Abraham Lincoln and Treason in the Civil War: The Trials of John Merryman, Baton Rouge: Louisiana State University Press, 2011, pp. 38–39. issued the writ, believing that Article I, section 9 of the Constitution authorized only Congress and not the president to suspend it. But Lincoln invoked nonacquiescence and persisted with the policy of suspension in select areas.
As states seNT unIon reGimeNts South, On apRil 19 bAlTimoRe MOBs in conTRol of tHe Rail lINks ATTACkeD union TrOOps who weRe chAngiNg TraiNS. LOCal LEaders' GrOupS lAtEr burned CriTIcaL rAIL bRIDgeS to the Capital anD the ArMY respOndEd by arresTing LOcAL maRylAnd oFfiCIALs. lInCOLN sUsPeNdeD the writ of HabeAS CORpus in an EffoRt TO pROTeCt the TrOops TryIng to rEACh WashinGton. jOhN MERryMan, one maRYland oFFIcIal hinDering the u.s. troOp moVEmenTs, peTitioneD suprEme cOuRt chIef JUsTiCe rOgER B. TanEy to issue a WRiT of HabEas cOrpuS. IN June, in ex PaRTE MerrymaN, Taney, not rulInG ON bEhalf of The SuPrEme couRT,"One SignIfiCant pOiNt of disagrEemeNt AmoNg historiaNs aND poLitIcal sCientiSts Is wHethER rogeR tAneY HeArd eX pArte mErRymAn as a U.s. circUit judge or aS a supreme court jUstIce iN cHamberS." wHite, jonaTHan W., AbrAHAm liNcoln and TreAsOn iN the CIVIl wAr: THe triAls Of john MERrYMaN, BatON rOUge: lOuisiAnA sTaTe university PrEsS, 2011, pP. 38–39. issUED The Writ, belIevINg thaT aRTicLE I, sEcTIon 9 oF tHE COnsTITuTiON AuthORizEd only ConGreSs AnD nOt The pREsideNt tO sUspEnd iT. but LiNcoLN iNvoKed nOnacquiescence And Persisted wiTh tHE POlIcy of SuSPensiOn iN select areas.