st all State remedies; and even after the State courts have
acted, the federal courts will usually leave the prisoner to the usual
and orderly procedure of appeal to the Supreme Court. Furthermore, the
Supreme Court will, in the exercise of a sound discretion, issue a writ
of mandamus to compel a federal court to remand to a State court a
prosecution of a federal officer removed to it, when it appears that the
officer in question, in seeking removal, failed to make a candid,
specific, and positive explanation of his relation to the transaction
giving rise to the crime for which he was indicted.[697]

Because of the care with which the discretion to issue writs of _habeas
corpus_ and to grant removals has been exercised by the federal courts
to release persons from State custody there has been a minimum of
friction in this area of federal-state relations, in contrast to that
produced by their extensive use of injunctions to restrain the
enforcement of State statutes. In Wade _v._ Mayo,[698] Justice Murphy
cited the statistics of the Administrative Office of the United States
Courts which revealed that during the fiscal years of 1943, 1944, and
1945, there was an average of 451 _habeas corpus_ petitions filed each
year in federal district courts by persons in State custody, and that of
these petitions, an average of only six per year resulted in a reversal
of the conviction and the release of the prisoner.

COMITY AS COOPERATION

Moreover, cold comity may become on occasion warm cooperation between
the two systems of courts. In Ponzi _v._ Fessenden,[699] the matter at
issue was the authority of the Attorney General of the United States to
consent to the transfer on a writ of _habeas corpus_ of a federal
prisoner to a State court to be there put on trial upon indictments
there pending against him. The Court, speaking by Chief Justice Taft,
while conceding that there was no express statutory authority for such
action, sustained it. Said the Chief Justice: "We live in the
jurisdiction of two sovereignties, each having its own system of courts
to declare and enforce its laws in common territory. It would be
impossible for such courts to fulfil their respective functions without
embarrassing conflict unless rules were adopted by them to avoid it. The
people for whose benefit these two systems are maintained are deeply
interested that each system shall be effective and unhindered in its
vindication of its laws. The situatio